Problems while switching activity using intent

Problems while switching activity using intent - java

I am trying to create a student management application. So far I have made a login page. I am a beginner to android so I have downloaded another sample activity to understand how to link to activites using intent. So far as soon as I click on login, the app crashes. Could anyone help me understand what is going wrong?
This is my Login Page (MainActivity.java).
package zade.example.com.zade;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity extends Activity {
private EditText username = null;
private EditText password = null;
private Button login;
int counter = 3;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
username = (EditText) findViewById(R.id.eno);
password = (EditText) findViewById(R.id.password);
login = (Button) findViewById(R.id.login_button);
}
public void login(View view) {
if (username.getText().toString().equals("1") &&
password.getText().toString().equals("a")) {
Toast.makeText(getApplicationContext(), "Login Successful",
Toast.LENGTH_SHORT).show();
Intent intent = new Intent(this, Home.class);
this.startActivity ( intent );
}
else {
Toast.makeText(getApplicationContext(), "Wrong Credentials",
Toast.LENGTH_SHORT).show();
counter--;
if (counter == 0) {
login.setEnabled(false);
}
}
}
}
This is the Home.java (Home activity)
package zade.example.com.zade;
import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentManager;
import android.app.SearchManager;
import android.content.Intent;
import android.content.res.Configuration;
import android.os.Bundle;
import android.support.v4.app.ActionBarDrawerToggle;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.Toast;
import java.util.Locale;
public class Home extends Activity {
private DrawerLayout mDrawerLayout;
private ListView mDrawerList;
private ActionBarDrawerToggle mDrawerToggle;
private CharSequence mDrawerTitle;
private CharSequence mTitle;
private String[] mPlanetTitles;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
Intent intent = getIntent();
mTitle = mDrawerTitle = getTitle();
mPlanetTitles = getResources().getStringArray(R.array.planets_array);
mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
mDrawerList = (ListView) findViewById(R.id.left_drawer);
// set a custom shadow that overlays the main content when the drawer opens
mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START);
// set up the drawer's list view with items and click listener
mDrawerList.setAdapter(new ArrayAdapter<String>(this,
R.layout.drawer_list_item, mPlanetTitles));
mDrawerList.setOnItemClickListener(new DrawerItemClickListener());
// enable ActionBar app icon to behave as action to toggle nav drawer
getActionBar().setDisplayHomeAsUpEnabled(true);
getActionBar().setHomeButtonEnabled(true);
// ActionBarDrawerToggle ties together the the proper interactions
// between the sliding drawer and the action bar app icon
mDrawerToggle = new ActionBarDrawerToggle(
this, /* host Activity */
mDrawerLayout, /* DrawerLayout object */
R.drawable.ic_drawer, /* nav drawer image to replace 'Up' caret */
R.string.drawer_open, /* "open drawer" description for accessibility */
R.string.drawer_close /* "close drawer" description for accessibility */
) {
public void onDrawerClosed(View view) {
getActionBar().setTitle(mTitle);
invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()
}
public void onDrawerOpened(View drawerView) {
getActionBar().setTitle(mDrawerTitle);
invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()
}
};
mDrawerLayout.setDrawerListener(mDrawerToggle);
if (savedInstanceState == null) {
selectItem(0);
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu_home, menu);
return super.onCreateOptionsMenu(menu);
}
/* Called whenever we call invalidateOptionsMenu() */
#Override
public boolean onPrepareOptionsMenu(Menu menu) {
// If the nav drawer is open, hide action items related to the content view
boolean drawerOpen = mDrawerLayout.isDrawerOpen(mDrawerList);
menu.findItem(R.id.action_websearch).setVisible(!drawerOpen);
return super.onPrepareOptionsMenu(menu);
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// The action bar home/up action should open or close the drawer.
// ActionBarDrawerToggle will take care of this.
if (mDrawerToggle.onOptionsItemSelected(item)) {
return true;
}
// Handle action buttons
switch(item.getItemId()) {
case R.id.action_websearch:
// create intent to perform web search for this planet
Intent intent = new Intent(Intent.ACTION_WEB_SEARCH);
intent.putExtra(SearchManager.QUERY, getActionBar().getTitle());
// catch event that there's no activity to handle intent
if (intent.resolveActivity(getPackageManager()) != null) {
startActivity(intent);
} else {
Toast.makeText(this, R.string.app_not_available, Toast.LENGTH_LONG).show();
}
return true;
default:
return super.onOptionsItemSelected(item);
}
}
/* The click listner for ListView in the navigation drawer */
private class DrawerItemClickListener implements ListView.OnItemClickListener {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
selectItem(position);
}
}
private void selectItem(int position) {
// update the main content by replacing fragments
Fragment fragment = new PlanetFragment();
Bundle args = new Bundle();
args.putInt(PlanetFragment.ARG_PLANET_NUMBER, position);
fragment.setArguments(args);
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction().replace(R.id.content_frame, fragment).commit();
// update selected item and title, then close the drawer
mDrawerList.setItemChecked(position, true);
setTitle(mPlanetTitles[position]);
mDrawerLayout.closeDrawer(mDrawerList);
}
#Override
public void setTitle(CharSequence title) {
mTitle = title;
getActionBar().setTitle(mTitle);
}
/**
* When using the ActionBarDrawerToggle, you must call it during
* onPostCreate() and onConfigurationChanged()...
*/
#Override
protected void onPostCreate(Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
// Sync the toggle state after onRestoreInstanceState has occurred.
mDrawerToggle.syncState();
}
#Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
// Pass any configuration change to the drawer toggls
mDrawerToggle.onConfigurationChanged(newConfig);
}
/**
* Fragment that appears in the "content_frame", shows a planet
*/
public static class PlanetFragment extends Fragment {
public static final String ARG_PLANET_NUMBER = "planet_number";
public PlanetFragment() {
// Empty constructor required for fragment subclasses
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_planet, container, false);
int i = getArguments().getInt(ARG_PLANET_NUMBER);
String planet = getResources().getStringArray(R.array.planets_array)[i];
int imageId = getResources().getIdentifier(planet.toLowerCase(Locale.getDefault()),
"drawable", getActivity().getPackageName());
((ImageView) rootView.findViewById(R.id.image)).setImageResource(imageId);
getActivity().setTitle(planet);
return rootView;
}
}
}
Logcat
--------- beginning of crash
01-19 14:35:25.458 2116-2116/zade.example.com.zade E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: zade.example.com.zade, PID: 2116
java.lang.RuntimeException: Unable to start activity ComponentInfo{zade.example.com.zade/zade.example.com.zade.Home}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setDisplayHomeAsUpEnabled(boolean)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setDisplayHomeAsUpEnabled(boolean)' on a null object reference
at zade.example.com.zade.Home.onCreate(Home.java:55)
at android.app.Activity.performCreate(Activity.java:5933)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
            at android.app.ActivityThread.access$800(ActivityThread.java:144)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Manifest:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="zade.example.com.zade" >
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".Home"
android:label="#string/title_activity_home"
android:parentActivityName=".MainActivity" >
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="zade.example.com.zade.MainActivity" />
</activity>
</application>
</manifest>

Instead of using
getActionBar().setDisplayHomeAsUpEnabled(true);
getActionBar().setHomeButtonEnabled(true);
use
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setHomeButtonEnabled(true);
Also make sure that you use getSupportActionBar() in place of getActionBar() in all occurrences.

This is because you are getting null when you are using getActionBar() as in LogCat it say
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setDisplayHomeAsUpEnabled(boolean)' on a null object reference
Use getSupportActionBar(), hope it helps.
If you are still getting the crash after doing this please tell me.

Check whether you added the second activity class in your AndroidManifest.XML file as a child of tag.
the following code might help:
login = (Button) findViewById(R.id.login_button);
login.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
//change the page and other stuffs you wish to when
//user will hit logIn button
}
});

It should not be so hard
1)Create 2 java files Activity1.java and activity2.java create suitables xml files if you want.
2)declare the second activity in the manifest.xml file within the
<Application> </Application tags.
in this activities onCreate write the following code
Intent intent = new Intent(this,Activity2.class);
startActivity(intent);

Related

Crashing app while using search bar in action bar in android. MainActivity is not able decide which one has to be executed first?

`Error in text
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.flavourbasket.flavourbasket/com.flavourbasket.flavourbasket.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.app.ActionBar.setDisplayHomeAsUpEnabled(boolean)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2778)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856)
at android.app.ActivityThread.-wrap11(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6494)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.app.ActionBar.setDisplayHomeAsUpEnabled(boolean)' on a null object reference
at com.flavourbasket.flavourbasket.MainActivity.navigationDrawer(MainActivity.java:50)
at com.flavourbasket.flavourbasket.MainActivity.onCreate(MainActivity.java:30)
at android.app.Activity.performCreate(Activity.java:7009)
at android.app.Activity.performCreate(Activity.java:7000)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1214)
`https://github.com/nippynic93/FlavourBaske
This link refers to my project which has the issue.
This is the Code Which has the error at 50th line. I am unable to find it please help me.
It contains Search Bar at the mainActivity. If I am going to comment the 50th line so my action bar got to disappear. And project runs fine.
package com.flavourbasket.flavourbasket;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.design.widget.BottomNavigationView;
import android.support.design.widget.NavigationView;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.view.MenuItem;
import android.widget.VideoView;
public class MainActivity extends AppCompatActivity {
private DrawerLayout mdrawerlayout;
private ActionBarDrawerToggle mtoggle;
NavigationView navigationview;
BottomNavigationView mBottomNav;
private VideoView videoView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
onInitialize();
navigationDrawer();
sideView();
videoView = findViewById(R.id.videoView);
videoView.setVideoPath("android.resource://"+getPackageName()+"/"+R.raw.video);
videoView.start();
}
public void onInitialize() {
mdrawerlayout = (DrawerLayout) findViewById(R.id.drawer);
navigationview = (NavigationView) findViewById(R.id.navigation);
mBottomNav = (BottomNavigationView) findViewById(R.id.bottom_navigation);
}
public void navigationDrawer() {
mtoggle = new ActionBarDrawerToggle(this, mdrawerlayout, R.string.open, R.string.close);
mdrawerlayout.addDrawerListener(mtoggle);
mtoggle.syncState();
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
navigationview.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem item) {
switch (item.getItemId()) {
case R.id.youtube_videos:
Intent i = new Intent(Intent.ACTION_VIEW, Uri.parse("https://www.youtube.com/user/flavourbasket"));
startActivity(i);
mdrawerlayout.closeDrawers();
break;
}
return true;
}
});
}
public void sideView() {
mBottomNav.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem item) {
// handle desired action here
// One possibility of action is to replace the contents above the nav bar
// return true if you want the item to be displayed as the selected item
switch (item.getItemId()) {
case R.id.extra_id:
Intent i = new Intent(MainActivity.this, Extras.class);
startActivity(i);
break;
}
return true;
}
});
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
if(mtoggle.onOptionsItemSelected(item)) {
return true;
}
return super.onOptionsItemSelected(item);
}
}

The ActionBar can be null. The code below will work:
toolbar = findViewById(R.id.tools);
setSupportActionBar(toolbar);
ActionBar ab = ((AppCompatActivity)getActivity()).getSupportActionBar();
if (ab != null) {
ab.setDisplayHomeAsUpEnabled(true);
}

RuntimeException on newly created NavDrawer

So, I'm a newbie with Android app development, and I'm getting the following error on a newly create Navigation Drawer activity (Incoming Stack trace):
04-01 16:50:52.113 8917-8917/pt.bluecover.wearable3d E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{pt.bluecover.wearable3d/pt.bluecover.wearable3d.DrawerActivity}: android.view.InflateException: Binary XML file line #18: Error inflating class fragment
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2306)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2358)
at android.app.ActivityThread.access$600(ActivityThread.java:156)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1340)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:153)
at android.app.ActivityThread.main(ActivityThread.java:5297)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
at dalvik.system.NativeStart.main(Native Method)
Caused by: android.view.InflateException: Binary XML file line #18: Error inflating class fragment
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:704)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:746)
at android.view.LayoutInflater.inflate(LayoutInflater.java:489)
at android.view.LayoutInflater.inflate(LayoutInflater.java:396)
at android.view.LayoutInflater.inflate(LayoutInflater.java:352)
at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:274)
at android.app.Activity.setContentView(Activity.java:1881)
at pt.bluecover.wearable3d.DrawerActivity.onCreate(DrawerActivity.java:37)
at android.app.Activity.performCreate(Activity.java:5122)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1081)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2270)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2358) 
at android.app.ActivityThread.access$600(ActivityThread.java:156) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1340) 
at android.os.Handler.dispatchMessage(Handler.java:99) 
at android.os.Looper.loop(Looper.java:153) 
at android.app.ActivityThread.main(ActivityThread.java:5297) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:511) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600) 
at dalvik.system.NativeStart.main(Native Method) 
Caused by: java.lang.NullPointerException
at pt.bluecover.wearable3d.NavigationDrawerFragment.onCreateView(NavigationDrawerFragment.java:101)
at android.app.Fragment.performCreateView(Fragment.java:1695)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:861)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1035)
at android.app.FragmentManagerImpl.addFragment(FragmentManager.java:1137)
at android.app.Activity.onCreateView(Activity.java:4735)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:680)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:746) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:489) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:396) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:352) 
at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:274) 
at android.app.Activity.setContentView(Activity.java:1881) 
at pt.bluecover.wearable3d.DrawerActivity.onCreate(DrawerActivity.java:37) 
at android.app.Activity.performCreate(Activity.java:5122) 
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1081) 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2270) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2358) 
at android.app.ActivityThread.access$600(ActivityThread.java:156) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1340) 
at android.os.Handler.dispatchMessage(Handler.java:99) 
at android.os.Looper.loop(Looper.java:153) 
at android.app.ActivityThread.main(ActivityThread.java:5297) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:511) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600) 
at dalvik.system.NativeStart.main(Native Method) 
I also have the following classes referenced in the trace:
package pt.bluecover.wearable3d;
import android.app.Activity;
import android.app.ActionBar;
import android.app.Fragment;
import android.app.FragmentManager;
import android.content.Context;
import android.os.Build;
import android.os.Bundle;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.support.v4.widget.DrawerLayout;
import android.widget.ArrayAdapter;
import android.widget.TextView;
public class DrawerActivity extends Activity
implements NavigationDrawerFragment.NavigationDrawerCallbacks {
/**
* Fragment managing the behaviors, interactions and presentation of the navigation drawer.
*/
private NavigationDrawerFragment mNavigationDrawerFragment;
/**
* Used to store the last screen title. For use in {#link #restoreActionBar()}.
*/
private CharSequence mTitle;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_drawer);
mNavigationDrawerFragment = (NavigationDrawerFragment)
getFragmentManager().findFragmentById(R.id.navigation_drawer);
mTitle = getTitle();
// Set up the drawer.
mNavigationDrawerFragment.setUp(
R.id.navigation_drawer,
(DrawerLayout) findViewById(R.id.drawer_layout));
}
#Override
public void onNavigationDrawerItemSelected(int position) {
// update the main content by replacing fragments
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction()
.replace(R.id.container, PlaceholderFragment.newInstance(position + 1))
.commit();
}
public void onSectionAttached(int number) {
switch (number) {
case 1:
mTitle = getString(R.string.title_section1);
break;
case 2:
mTitle = getString(R.string.title_section2);
break;
case 3:
mTitle = getString(R.string.title_section3);
break;
}
}
public void restoreActionBar() {
ActionBar actionBar = getActionBar();
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
actionBar.setDisplayShowTitleEnabled(true);
actionBar.setTitle(mTitle);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
public PlaceholderFragment() {
}
/**
* Returns a new instance of this fragment for the given section
* number.
*/
public static PlaceholderFragment newInstance(int sectionNumber) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_drawer, container, false);
return rootView;
}
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
((DrawerActivity) activity).onSectionAttached(
getArguments().getInt(ARG_SECTION_NUMBER));
}
}
}
And this one:
package pt.bluecover.wearable3d;
import android.app.Activity;
import android.app.ActionBar;
import android.app.Fragment;
import android.support.v4.app.ActionBarDrawerToggle;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.content.SharedPreferences;
import android.content.res.Configuration;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;
/**
* Fragment used for managing interactions for and presentation of a navigation drawer.
* See the <a href="https://developer.android.com/design/patterns/navigation-drawer.html#Interaction">
* design guidelines</a> for a complete explanation of the behaviors implemented here.
*/
public class NavigationDrawerFragment extends Fragment {
/**
* Remember the position of the selected item.
*/
private static final String STATE_SELECTED_POSITION = "selected_navigation_drawer_position";
/**
* Per the design guidelines, you should show the drawer on launch until the user manually
* expands it. This shared preference tracks this.
*/
private static final String PREF_USER_LEARNED_DRAWER = "navigation_drawer_learned";
/**
* A pointer to the current callbacks instance (the Activity).
*/
private NavigationDrawerCallbacks mCallbacks;
/**
* Helper component that ties the action bar to the navigation drawer.
*/
private ActionBarDrawerToggle mDrawerToggle;
private DrawerLayout mDrawerLayout;
private ListView mDrawerListView;
private View mFragmentContainerView;
private int mCurrentSelectedPosition = 0;
private boolean mFromSavedInstanceState;
private boolean mUserLearnedDrawer;
public NavigationDrawerFragment() {
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Read in the flag indicating whether or not the user has demonstrated awareness of the
// drawer. See PREF_USER_LEARNED_DRAWER for details.
SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(getActivity());
mUserLearnedDrawer = sp.getBoolean(PREF_USER_LEARNED_DRAWER, false);
if (savedInstanceState != null) {
mCurrentSelectedPosition = savedInstanceState.getInt(STATE_SELECTED_POSITION);
mFromSavedInstanceState = true;
}
// Select either the default item (0) or the last selected item.
selectItem(mCurrentSelectedPosition);
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
// Indicate that this fragment would like to influence the set of actions in the action bar.
setHasOptionsMenu(true);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
mDrawerListView = (ListView) inflater.inflate(
R.layout.drawer_drawer, container, false);
mDrawerListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
selectItem(position);
}
});
mDrawerListView.setAdapter(new ArrayAdapter<String>(
getActionBar().getThemedContext(),
android.R.layout.simple_list_item_activated_1,
android.R.id.text1,
new String[]{
getString(R.string.title_section1),
getString(R.string.title_section2),
getString(R.string.title_section3),
}));
mDrawerListView.setItemChecked(mCurrentSelectedPosition, true);
return mDrawerListView;
}
public boolean isDrawerOpen() {
return mDrawerLayout != null && mDrawerLayout.isDrawerOpen(mFragmentContainerView);
}
/**
* Users of this fragment must call this method to set up the navigation drawer interactions.
*
* #param fragmentId The android:id of this fragment in its activity's layout.
* #param drawerLayout The DrawerLayout containing this fragment's UI.
*/
public void setUp(int fragmentId, DrawerLayout drawerLayout) {
mFragmentContainerView = getActivity().findViewById(fragmentId);
mDrawerLayout = drawerLayout;
// set a custom shadow that overlays the main content when the drawer opens
mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START);
// set up the drawer's list view with items and click listener
ActionBar actionBar = getActionBar();
actionBar.setDisplayHomeAsUpEnabled(true);
actionBar.setHomeButtonEnabled(true);
// ActionBarDrawerToggle ties together the the proper interactions
// between the navigation drawer and the action bar app icon.
mDrawerToggle = new ActionBarDrawerToggle(
getActivity(), /* host Activity */
mDrawerLayout, /* DrawerLayout object */
R.drawable.ic_drawer, /* nav drawer image to replace 'Up' caret */
R.string.navigation_drawer_open, /* "open drawer" description for accessibility */
R.string.navigation_drawer_close /* "close drawer" description for accessibility */
) {
#Override
public void onDrawerClosed(View drawerView) {
super.onDrawerClosed(drawerView);
if (!isAdded()) {
return;
}
getActivity().invalidateOptionsMenu(); // calls onPrepareOptionsMenu()
}
#Override
public void onDrawerOpened(View drawerView) {
super.onDrawerOpened(drawerView);
if (!isAdded()) {
return;
}
if (!mUserLearnedDrawer) {
// The user manually opened the drawer; store this flag to prevent auto-showing
// the navigation drawer automatically in the future.
mUserLearnedDrawer = true;
SharedPreferences sp = PreferenceManager
.getDefaultSharedPreferences(getActivity());
sp.edit().putBoolean(PREF_USER_LEARNED_DRAWER, true).apply();
}
getActivity().invalidateOptionsMenu(); // calls onPrepareOptionsMenu()
}
};
// If the user hasn't 'learned' about the drawer, open it to introduce them to the drawer,
// per the navigation drawer design guidelines.
if (!mUserLearnedDrawer && !mFromSavedInstanceState) {
mDrawerLayout.openDrawer(mFragmentContainerView);
}
// Defer code dependent on restoration of previous instance state.
mDrawerLayout.post(new Runnable() {
#Override
public void run() {
mDrawerToggle.syncState();
}
});
mDrawerLayout.setDrawerListener(mDrawerToggle);
}
private void selectItem(int position) {
mCurrentSelectedPosition = position;
if (mDrawerListView != null) {
mDrawerListView.setItemChecked(position, true);
}
if (mDrawerLayout != null) {
mDrawerLayout.closeDrawer(mFragmentContainerView);
}
if (mCallbacks != null) {
mCallbacks.onNavigationDrawerItemSelected(position);
}
}
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
try {
mCallbacks = (NavigationDrawerCallbacks) activity;
} catch (ClassCastException e) {
throw new ClassCastException("Activity must implement NavigationDrawerCallbacks.");
}
}
#Override
public void onDetach() {
super.onDetach();
mCallbacks = null;
}
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putInt(STATE_SELECTED_POSITION, mCurrentSelectedPosition);
}
#Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
// Forward the new configuration the drawer toggle component.
mDrawerToggle.onConfigurationChanged(newConfig);
}
#Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
// If the drawer is open, show the global app actions in the action bar. See also
// showGlobalContextActionBar, which controls the top-left area of the action bar.
if (mDrawerLayout != null && isDrawerOpen()) {
inflater.inflate(R.menu.global, menu);
showGlobalContextActionBar();
}
super.onCreateOptionsMenu(menu, inflater);
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
if (mDrawerToggle.onOptionsItemSelected(item)) {
return true;
}
if (item.getItemId() == R.id.action_example) {
Toast.makeText(getActivity(), "Example action.", Toast.LENGTH_SHORT).show();
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* Per the navigation drawer design guidelines, updates the action bar to show the global app
* 'context', rather than just what's in the current screen.
*/
private void showGlobalContextActionBar() {
ActionBar actionBar = getActionBar();
actionBar.setDisplayShowTitleEnabled(true);
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
actionBar.setTitle(R.string.app_name);
}
private ActionBar getActionBar() {
return getActivity().getActionBar();
}
/**
* Callbacks interface that all activities using this fragment must implement.
*/
public static interface NavigationDrawerCallbacks {
/**
* Called when an item in the navigation drawer is selected.
*/
void onNavigationDrawerItemSelected(int position);
}
}
Both where auto-generated by adding a Navigation Drawer Activity to the project and haven't been modified yet...
EDIT: activity_drawer.xml code here:
<!-- A DrawerLayout is intended to be used as the top-level content view using match_parent for both width and height to consume the full space available. -->
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="pt.bluecover.wearable3d.DrawerActivity">
<!-- As the main content view, the view below consumes the entire
space available using match_parent in both dimensions. -->
<FrameLayout
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<!-- The drawer is given a fixed width in dp and extends the full height of
the container. -->
<fragment
android:id="#+id/navigation_drawer"
android:name="pt.bluecover.wearable3d.NavigationDrawerFragment"
android:layout_width="#dimen/navigation_drawer_width"
android:layout_height="match_parent"
android:layout_gravity="start"
tools:layout="#layout/drawer_drawer" />
</android.support.v4.widget.DrawerLayout>

Not sure why you need a themed context for an Adapter, but this section is throwing a NullPointerException.
mDrawerListView.setAdapter(new ArrayAdapter<String>(
getActionBar().getThemedContext(),
android.R.layout.simple_list_item_activated_1,
android.R.id.text1,
new String[]{
getString(R.string.title_section1),
getString(R.string.title_section2),
getString(R.string.title_section3),
}));
Try using getActivity() instead of getActionBar().getThemedContext() because getActionBar() will return null if you aren't using a theme in styles.xml that contains an ActionBar for the parent Activity.
In code...
mDrawerListView.setAdapter(new ArrayAdapter<String>(
getActivity(), ...

Make sure you are not using Theme.AppCompat.Light.NoActionBar. To be able to get the action bar you should have it in the theme.
android:Theme.Light
will do. In your styles.xml use this for the Theme that you are using for the activity in AndroidManifest.xml
<style name="AppTheme" parent="android:Theme.Light">

Attempt to invoke virtual method 'void android.app.ActionBar.setDisplayHomeAsUpEnabled(boolean)' on a null object reference NullPointer [duplicate]

This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 7 years ago.
Having a few run-time issues with a navigation drawer i'm trying to test out...
The error I get is:
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.suzan.parentmeetme/com.example.suzan.parentmeetme.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setDisplayHomeAsUpEnabled(boolean)' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setDisplayHomeAsUpEnabled(boolean)' on a null object reference
at com.example.suzan.parentmeetme.NavigationDrawerFragment.setUp(NavigationDrawerFragment.java:138)
at com.example.suzan.parentmeetme.MainActivity.onCreate(MainActivity.java:35)
at android.app.Activity.performCreate(Activity.java:6237)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) 
at android.app.ActivityThread.-wrap11(ActivityThread.java) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:148) 
at android.app.ActivityThread.main(ActivityThread.java:5417) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
12-30 21:45:47.250 27145-27145/? I/Process: Sending signal. PID: 27145 SIG: 9
I have a couple of java files:
MainActivity.java
package com.example.suzan.parentmeetme;
import android.app.ActionBar;
import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentManager;
import android.os.Bundle;
import android.support.v4.widget.DrawerLayout;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
public class MainActivity extends Activity
implements NavigationDrawerFragment.NavigationDrawerCallbacks {
// This navigation drawer frag will be responsible for the actions and behaviour of
// the navigation drawer
private NavigationDrawerFragment mNavigationDrawerFragment;
// Keeps track of the last screen we were on by storing the title name
private CharSequence mTitle;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mNavigationDrawerFragment = (NavigationDrawerFragment)getFragmentManager()
.findFragmentById(R.id.navigation_drawer);
mTitle = getTitle();
// Initialise the navigation drawer
mNavigationDrawerFragment.setUp(R.id.navigation_drawer, (DrawerLayout) findViewById(R.id.drawer_layout));
}
#Override
public void onNavigationDrawerItemSelected(int position)
{
Fragment fragment = null;
switch (position)
{
case 0:
fragment = new SettingsFragment();
break;
}
// update the main content by replacing fragments
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction().replace(R.id.container, fragment).commit();
}
public void onSectionAttached(int number)
{
switch (number)
{
case 1:
mTitle = getString(R.string.title_section1);
break;
}
}
public void restoreActionBar()
{
ActionBar actionBar = getActionBar();
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
actionBar.setDisplayShowTitleEnabled(true);
actionBar.setTitle(mTitle);
}
#Override
public boolean onCreateOptionsMenu(Menu menu)
{
if (!mNavigationDrawerFragment.isDrawerOpen())
{
// only display actions relevant to this screen
getMenuInflater().inflate(R.menu.sample, menu);
restoreActionBar();
return true;
}
return super.onCreateOptionsMenu(menu);
}
#Override
public boolean onOptionsItemSelected(MenuItem item)
{
// Handle action bar item clicks here.
// Action bar will handle clicks on home/up
// button, so long as parent activity is specified
// in AndroidManifest.xml
int id = item.getItemId();
if (id == R.id.action_settings)
{
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment
{
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
/**
* Returns a new instance of this fragment for the given section
* number.
*/
public static PlaceholderFragment newInstance(int sectionNumber) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_layout, container, false);
return rootView;
}
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
((MainActivity) activity).onSectionAttached(
getArguments().getInt(ARG_SECTION_NUMBER));
}
}
}
NavigationDrawerFragment.java
package com.example.suzan.parentmeetme;
/**
* Created by Suzan on 30/12/2015.
*/
import android.app.Activity;
import android.app.ActionBar;
import android.app.Fragment;
import android.support.v4.app.ActionBarDrawerToggle;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.content.SharedPreferences;
import android.content.res.Configuration;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;
/**
* Fragment used for managing interactions for and presentation of a navigation drawer.
* See the <a href="https://developer.android.com/design/patterns/navigation-drawer.html#Interaction">
* design guidelines</a> for a complete explanation of the behaviors implemented here.
*/
public class NavigationDrawerFragment extends Fragment {
/**
* Remember the position of the selected item.
*/
private static final String STATE_SELECTED_POSITION = "selected_navigation_drawer_position";
/**
* Per the design guidelines, you should show the drawer on launch until the user manually
* expands it. This shared preference tracks this.
*/
private static final String PREF_USER_LEARNED_DRAWER = "navigation_drawer_learned";
/**
* A pointer to the current callbacks instance (the Activity).
*/
private NavigationDrawerCallbacks mCallbacks;
/**
* Helper component that ties the action bar to the navigation drawer.
*/
private ActionBarDrawerToggle mDrawerToggle;
private DrawerLayout mDrawerLayout;
private ListView mDrawerListView;
private View mFragmentContainerView;
private int mCurrentSelectedPosition = 0;
private boolean mFromSavedInstanceState;
private boolean mUserLearnedDrawer;
public NavigationDrawerFragment() {
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Read in the flag indicating whether or not the user has demonstrated awareness of the
// drawer. See PREF_USER_LEARNED_DRAWER for details.
SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(getActivity());
mUserLearnedDrawer = sp.getBoolean(PREF_USER_LEARNED_DRAWER, false);
if (savedInstanceState != null) {
mCurrentSelectedPosition = savedInstanceState.getInt(STATE_SELECTED_POSITION);
mFromSavedInstanceState = true;
}
// Select either the default item (0) or the last selected item.
selectItem(mCurrentSelectedPosition);
}
#Override
public void onActivityCreated (Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
// Indicate that this fragment would like to influence the set of actions in the action bar.
setHasOptionsMenu(true);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View myParentView = inflater.inflate(
R.layout.fragment_navigation_drawer, container, false);
mDrawerListView = (ListView) myParentView.findViewById(R.id.listview);
// the listview is the id you gave to you listview in xml
mDrawerListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
selectItem(position);
}
});
mDrawerListView.setAdapter(new ArrayAdapter<String>(
getActivity(),
android.R.layout.simple_list_item_activated_1,
android.R.id.text1,
new String[]{
getString(R.string.title_section1),
getString(R.string.title_section2),
getString(R.string.title_section3),
}));
mDrawerListView.setItemChecked(mCurrentSelectedPosition, true);
return mDrawerListView;
}
public boolean isDrawerOpen() {
return mDrawerLayout != null && mDrawerLayout.isDrawerOpen(mFragmentContainerView);
}
/**
* Users of this fragment must call this method to set up the navigation drawer interactions.
*
* #param fragmentId The android:id of this fragment in its activity's layout.
* #param drawerLayout The DrawerLayout containing this fragment's UI.
*/
public void setUp(int fragmentId, DrawerLayout drawerLayout) {
mFragmentContainerView = getActivity().findViewById(fragmentId);
mDrawerLayout = drawerLayout;
// set a custom shadow that overlays the main content when the drawer opens
mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START);
// set up the drawer's list view with items and click listener
ActionBar actionBar = getActionBar();
actionBar.setDisplayHomeAsUpEnabled(true);
actionBar.setHomeButtonEnabled(true);
// ActionBarDrawerToggle ties together the the proper interactions
// between the navigation drawer and the action bar app icon.
mDrawerToggle = new ActionBarDrawerToggle(
getActivity(), /* host Activity */
mDrawerLayout, /* DrawerLayout object */
R.drawable.ic_drawer, /* nav drawer image to replace 'Up' caret */
R.string.navigation_drawer_open, /* "open drawer" description for accessibility */
R.string.navigation_drawer_close /* "close drawer" description for accessibility */
) {
#Override
public void onDrawerClosed(View drawerView) {
super.onDrawerClosed(drawerView);
if (!isAdded()) {
return;
}
getActivity().invalidateOptionsMenu(); // calls onPrepareOptionsMenu()
}
#Override
public void onDrawerOpened(View drawerView) {
super.onDrawerOpened(drawerView);
if (!isAdded()) {
return;
}
if (!mUserLearnedDrawer) {
// The user manually opened the drawer; store this flag to prevent auto-showing
// the navigation drawer automatically in the future.
mUserLearnedDrawer = true;
SharedPreferences sp = PreferenceManager
.getDefaultSharedPreferences(getActivity());
sp.edit().putBoolean(PREF_USER_LEARNED_DRAWER, true).apply();
}
getActivity().invalidateOptionsMenu(); // calls onPrepareOptionsMenu()
}
};
// If the user hasn't 'learned' about the drawer, open it to introduce them to the drawer,
// per the navigation drawer design guidelines.
if (!mUserLearnedDrawer && !mFromSavedInstanceState) {
mDrawerLayout.openDrawer(mFragmentContainerView);
}
// Defer code dependent on restoration of previous instance state.
mDrawerLayout.post(new Runnable() {
#Override
public void run() {
mDrawerToggle.syncState();
}
});
mDrawerLayout.setDrawerListener(mDrawerToggle);
}
private void selectItem(int position) {
mCurrentSelectedPosition = position;
if (mDrawerListView != null) {
mDrawerListView.setItemChecked(position, true);
}
if (mDrawerLayout != null) {
mDrawerLayout.closeDrawer(mFragmentContainerView);
}
if (mCallbacks != null) {
mCallbacks.onNavigationDrawerItemSelected(position);
}
}
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
try {
mCallbacks = (NavigationDrawerCallbacks) activity;
} catch (ClassCastException e) {
throw new ClassCastException("Activity must implement NavigationDrawerCallbacks.");
}
}
#Override
public void onDetach() {
super.onDetach();
mCallbacks = null;
}
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putInt(STATE_SELECTED_POSITION, mCurrentSelectedPosition);
}
#Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
// Forward the new configuration the drawer toggle component.
mDrawerToggle.onConfigurationChanged(newConfig);
}
#Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
// If the drawer is open, show the global app actions in the action bar. See also
// showGlobalContextActionBar, which controls the top-left area of the action bar.
if (mDrawerLayout != null && isDrawerOpen()) {
inflater.inflate(R.menu.global, menu);
showGlobalContextActionBar();
}
super.onCreateOptionsMenu(menu, inflater);
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
if (mDrawerToggle.onOptionsItemSelected(item)) {
return true;
}
if (item.getItemId() == R.id.action_example) {
Toast.makeText(getActivity(), "Example action.", Toast.LENGTH_SHORT).show();
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* Per the navigation drawer design guidelines, updates the action bar to show the global app
* 'context', rather than just what's in the current screen.
*/
private void showGlobalContextActionBar() {
ActionBar actionBar = getActionBar();
actionBar.setDisplayShowTitleEnabled(true);
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
actionBar.setTitle(R.string.app_name);
}
private ActionBar getActionBar() {
return getActivity().getActionBar();
}
/**
* Callbacks interface that all activities using this fragment must implement.
*/
public static interface NavigationDrawerCallbacks {
/**
* Called when an item in the navigation drawer is selected.
*/
void onNavigationDrawerItemSelected(int position);
}
}
And I've got a few XML files:
activity_main.xml
<!-- A DrawerLayout is intended to be used as the top-level content view using match_parent for both width and height to consume the full space available. -->
<android.support.v4.widget.DrawerLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<!-- As the main content view, the view below consumes the entire
space available using match_parent in both dimensions. -->
<FrameLayout
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<!-- android:layout_gravity="start" tells DrawerLayout to treat
this as a sliding drawer on the left side for left-to-right
languages and on the right side for right-to-left languages.
If you're not building against API 17 or higher, use
android:layout_gravity="left" instead. -->
<!-- The drawer is given a fixed width in dp and extends the full height of
the container. -->
<fragment android:id="#+id/navigation_drawer"
android:layout_width="#dimen/navigation_drawer_width"
android:layout_height="match_parent"
android:layout_gravity="start"
android:name="com.example.suzan.parentmeetme.NavigationDrawerFragment"
tools:layout="#layout/fragment_navigation_drawer" />
</android.support.v4.widget.DrawerLayout>
fragment_navigation_layout.xml
<ListView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:choiceMode="singleChoice"
android:divider="#android:color/transparent"
android:dividerHeight="0dp"
android:background="#cccc"
android:id="#+id/listview"
tools:context=".NavigationDrawerFragment" />
Could anyone figure out what I might be doing wrong? Been staring at this for hours and seriously can't work it out.....
Thanks!

Make sure you have referenced
public class MainActivity extends ActionBarActivity {
...
}
and change
ActionBar bar = getActionBar();
to
ActionBar bar =getActivity().getSupportActionBar();
Reference
http://developer.android.com/guide/topics/ui/actionbar.html

First change your class extension
public class MainActivity extends AppCompatActivity{
And then get your support action bar adding the following code to the 'onCreateView' method
assert getSupportActionBar() != null;
getSupportActionBar().setDisplayHomeAsUpEnabled(true);

Android sliding menu using navigation drawer

I am trying to work on a project which has sliding menu.But i want to run it on api level 8.So i used the support library for the result.But the app is force closing.The code for the main class is :
package info.androidhive.slidingmenu;
import info.androidhive.slidingmenu.adapter.NavDrawerListAdapter;
import info.androidhive.slidingmenu.model.NavDrawerItem;
import java.util.ArrayList;
import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentManager;
import android.content.res.Configuration;
import android.content.res.TypedArray;
import android.os.Bundle;
import android.support.v4.app.ActionBarDrawerToggle;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarActivity;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;
public class MainActivity extends ActionBarActivity {
private DrawerLayout mDrawerLayout;
private ListView mDrawerList;
private ActionBarDrawerToggle mDrawerToggle;
// nav drawer title
private CharSequence mDrawerTitle;
// used to store app title
private CharSequence mTitle;
// slide menu items
private String[] navMenuTitles;
private TypedArray navMenuIcons;
private ArrayList<NavDrawerItem> navDrawerItems;
private NavDrawerListAdapter adapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mTitle = mDrawerTitle = getTitle();
// load slide menu items
navMenuTitles = getResources().getStringArray(R.array.nav_drawer_items);
// nav drawer icons from resources
navMenuIcons = getResources()
.obtainTypedArray(R.array.nav_drawer_icons);
mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
mDrawerList = (ListView) findViewById(R.id.list_slidermenu);
navDrawerItems = new ArrayList<NavDrawerItem>();
// adding nav drawer items to array
// Home
navDrawerItems.add(new NavDrawerItem(navMenuTitles[0], navMenuIcons.getResourceId(0, -1)));
// Find People
navDrawerItems.add(new NavDrawerItem(navMenuTitles[1], navMenuIcons.getResourceId(1, -1)));
// Photos
navDrawerItems.add(new NavDrawerItem(navMenuTitles[2], navMenuIcons.getResourceId(2, -1)));
// Communities, Will add a counter here
navDrawerItems.add(new NavDrawerItem(navMenuTitles[3], navMenuIcons.getResourceId(3, -1), true, "22"));
// Pages
navDrawerItems.add(new NavDrawerItem(navMenuTitles[4], navMenuIcons.getResourceId(4, -1)));
// What's hot, We will add a counter here
navDrawerItems.add(new NavDrawerItem(navMenuTitles[5], navMenuIcons.getResourceId(5, -1), true, "50+"));
// Recycle the typed array
navMenuIcons.recycle();
mDrawerList.setOnItemClickListener(new SlideMenuClickListener());
// setting the nav drawer list adapter
adapter = new NavDrawerListAdapter(getApplicationContext(),
navDrawerItems);
mDrawerList.setAdapter(adapter);
// enabling action bar app icon and behaving it as toggle button
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setHomeButtonEnabled(true);
mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout,
R.drawable.ic_drawer, //nav menu toggle icon
R.string.app_name, // nav drawer open - description for accessibility
R.string.app_name // nav drawer close - description for accessibility
) {
public void onDrawerClosed(View view) {
getSupportActionBar().setTitle(mTitle);
// calling onPrepareOptionsMenu() to show action bar icons
//invalidateOptionsMenu();
supportInvalidateOptionsMenu();
}
public void onDrawerOpened(View drawerView) {
getSupportActionBar().setTitle(mDrawerTitle);
// calling onPrepareOptionsMenu() to hide action bar icons
//invalidateOptionsMenu();
supportInvalidateOptionsMenu();
}
};
mDrawerLayout.setDrawerListener(mDrawerToggle);
if (savedInstanceState == null) {
// on first time display view for first nav item
displayView(0);
}
}
/**
* Slide menu item click listener
* */
private class SlideMenuClickListener implements
ListView.OnItemClickListener {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {
// display view for selected nav drawer item
displayView(position);
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// toggle nav drawer on selecting action bar app icon/title
if (mDrawerToggle.onOptionsItemSelected(item)) {
return true;
}
// Handle action bar actions click
switch (item.getItemId()) {
case R.id.action_settings:
return true;
default:
return super.onOptionsItemSelected(item);
}
}
/* *
* Called when invalidateOptionsMenu() is triggered
*/
#Override
public boolean onPrepareOptionsMenu(Menu menu) {
// if nav drawer is opened, hide the action items
boolean drawerOpen = mDrawerLayout.isDrawerOpen(mDrawerList);
menu.findItem(R.id.action_settings).setVisible(!drawerOpen);
return super.onPrepareOptionsMenu(menu);
}
/**
* Diplaying fragment view for selected nav drawer list item
* */
private void displayView(int position) {
// update the main content by replacing fragments
android.support.v4.app.Fragment fragment = null;
switch (position) {
case 0:
fragment = new HomeFragment();
break;
case 1:
fragment = new FindPeopleFragment();
break;
case 2:
fragment = new PhotosFragment();
break;
case 3:
fragment = new CommunityFragment();
break;
case 4:
fragment = new PagesFragment();
break;
case 5:
fragment = new WhatsHotFragment();
break;
default:
break;
}
if (fragment != null) {
android.support.v4.app.FragmentManager fragmentManager = getSupportFragmentManager();
android.support.v4.app.FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.frame_container,fragment);
fragmentTransaction.commit();
// fragmentManager.beginTransaction()
// .replace(R.id.frame_container, fragment).commit();
// update selected item and title, then close the drawer
mDrawerList.setItemChecked(position, true);
mDrawerList.setSelection(position);
setTitle(navMenuTitles[position]);
mDrawerLayout.closeDrawer(mDrawerList);
} else {
// error in creating fragment
Log.e("MainActivity", "Error in creating fragment");
}
}
#Override
public void setTitle(CharSequence title) {
mTitle = title;
getSupportActionBar().setTitle(mTitle);
}
/**
* When using the ActionBarDrawerToggle, you must call it during
* onPostCreate() and onConfigurationChanged()...
*/
#Override
protected void onPostCreate(Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
// Sync the toggle state after onRestoreInstanceState has occurred.
mDrawerToggle.syncState();
}
#Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
// Pass any configuration change to the drawer toggls
mDrawerToggle.onConfigurationChanged(newConfig);
}
}
The LOGCAT:
08-20 14:29:44.687: E/AndroidRuntime(13141): FATAL EXCEPTION: main
08-20 14:29:44.687: E/AndroidRuntime(13141): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{info.androidhive.slidingmenu/info.androidhive.slidingmenu.MainActivity}: java.lang.ClassNotFoundException: info.androidhive.slidingmenu.MainActivity in loader dalvik.system.PathClassLoader[/data/app/info.androidhive.slidingmenu-1.apk]
08-20 14:29:44.687: E/AndroidRuntime(13141): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1573)
08-20 14:29:44.687: E/AndroidRuntime(13141): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1667)
08-20 14:29:44.687: E/AndroidRuntime(13141): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
08-20 14:29:44.687: E/AndroidRuntime(13141): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:935)
08-20 14:29:44.687: E/AndroidRuntime(13141): at android.os.Handler.dispatchMessage(Handler.java:99)
08-20 14:29:44.687: E/AndroidRuntime(13141): at android.os.Looper.loop(Looper.java:130)
08-20 14:29:44.687: E/AndroidRuntime(13141): at android.app.ActivityThread.main(ActivityThread.java:3689)
08-20 14:29:44.687: E/AndroidRuntime(13141): at java.lang.reflect.Method.invokeNative(Native Method)
08-20 14:29:44.687: E/AndroidRuntime(13141): at java.lang.reflect.Method.invoke(Method.java:507)
08-20 14:29:44.687: E/AndroidRuntime(13141): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:842)
08-20 14:29:44.687: E/AndroidRuntime(13141): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
08-20 14:29:44.687: E/AndroidRuntime(13141): at dalvik.system.NativeStart.main(Native Method)
08-20 14:29:44.687: E/AndroidRuntime(13141): Caused by: java.lang.ClassNotFoundException: info.androidhive.slidingmenu.MainActivity in loader dalvik.system.PathClassLoader[/data/app/info.androidhive.slidingmenu-1.apk]
08-20 14:29:44.687: E/AndroidRuntime(13141): at dalvik.system.PathClassLoader.findClass(PathClassLoader.java:240)
08-20 14:29:44.687: E/AndroidRuntime(13141): at java.lang.ClassLoader.loadClass(ClassLoader.java:551)
08-20 14:29:44.687: E/AndroidRuntime(13141): at java.lang.ClassLoader.loadClass(ClassLoader.java:511)
08-20 14:29:44.687: E/AndroidRuntime(13141): at android.app.Instrumentation.newActivity(Instrumentation.java:1021)
08-20 14:29:44.687: E/AndroidRuntime(13141): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1565)
08-20 14:29:44.687: E/AndroidRuntime(13141): ... 11 more
Please help!!

Don't know what you declared in manifest and menu file. However please check whether you declared this.
in manifest file:
<application
android:theme="#style/Theme.AppCompat">
in menu file:
xmlns:android="http://schemas.android.com/apk/res-auto
Check whether you mentioned this.

You are getting a class not found exception , this could be due to not building the app, try building the project and if still exist clean and build again.

I guess you haven't added MainActivity in your AndroidManifest.xml
Add below code inside <application> tag
<activity
android:name="info.androidhive.slidingmenu.MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

mDrawer can't work on android >3

I builded an app with simply webview and mDrawer slide menu. But after seeing that it's not working on > 3 android i have added a support library and made some changes but it's still not working.
here is the code
import android.annotation.SuppressLint;
import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.ActionBarDrawerToggle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentManager.OnBackStackChangedListener;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBar;
import android.support.v7.app.ActionBarActivity;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnKeyListener;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.ListView;
#SuppressLint("NewApi")
public class MainActivity extends ActionBarActivity {
private LayoutInflater mInflater;
private DrawerLayout mDrawerLayout;
WebView browser;
// ListView represents Navigation Drawer
private ListView mDrawerList;
// ActionBarDrawerToggle indicates the presence of Navigation Drawer in the action bar
private ActionBarDrawerToggle mDrawerToggle;
private String mTitle = "";
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
WebView browser = (WebView) findViewById(R.id.webView1);
browser.loadUrl("");
browser.setWebViewClient(new WebViewClient());
WebSettings webSettings = browser.getSettings();
webSettings.setJavaScriptEnabled(true);
mInflater = (LayoutInflater) getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
mDrawerList = (ListView) findViewById(R.id.drawer_list);
// Getting reference to the ActionBarDrawerToggle
mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout,
R.drawable.ic_drawer, R.string.drawer_open,
R.string.drawer_close) {
/** Called when drawer is closed */
public void onDrawerClosed(View view) {
getSupportActionBar().setTitle(mTitle);
invalidateOptionsMenu();
}
/** Called when a drawer is opened */
public void onDrawerOpened(View drawerView) {
getSupportActionBar().setTitle("Menu");
invalidateOptionsMenu();
}
};
browser.setOnKeyListener(new OnKeyListener()
{
public boolean onKey(View v, int keyCode, KeyEvent event)
{
if(event.getAction() == KeyEvent.ACTION_DOWN)
{
WebView webView = (WebView) v;
switch(keyCode)
{
case KeyEvent.KEYCODE_BACK:
if(webView.canGoBack())
{
webView.goBack();
return true;
}
break;
}
}
return false;
}
});
// Setting DrawerToggle on DrawerLayout
mDrawerLayout.setDrawerListener(mDrawerToggle);
// Creating an ArrayAdapter to add items to the listview mDrawerList
ArrayAdapter<String> adapter = new ArrayAdapter<String>(getBaseContext(),
R.layout.drawer_list_item, getResources().getStringArray(R.array.menus));
// Setting the adapter on mDrawerList
mDrawerList.setAdapter(adapter);
// Enabling Home button
getSupportActionBar().setHomeButtonEnabled(true);
// Enabling Up navigation
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
// Setting item click listener for the listview mDrawerList
mDrawerList.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// Getting an array of rivers
String[] menuItems = getResources().getStringArray(R.array.menus);
// Currently selected river
mTitle = menuItems[position];
// Creating a fragment object
// Passing selected item information to fragment
Bundle data = new Bundle();
data.putInt("position", position);
data.putString("url", getUrl(position));
// Getting reference to the FragmentManager
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.addOnBackStackChangedListener(new OnBackStackChangedListener() {
public void onBackStackChanged() {
if(getSupportFragmentManager().getBackStackEntryCount() == 0)
finish();
}
});
// Creating a fragment transaction
FragmentTransaction ft = fragmentManager.beginTransaction();
// Adding a fragment to the fragment transaction
// Committing the transaction
ft.commit();
// Closing the drawer
mDrawerLayout.closeDrawer(mDrawerList);
}
});
}
I have tried to change getActionBar() to getSupportActionBar() but i got next error:
The method getSupportActionBar() is undefined for the type new ActionBarDrawerToggle(){}
Logcat:
04-03 14:39:29.237: E/AndroidRuntime(687): FATAL EXCEPTION: main
04-03 14:39:29.237: E/AndroidRuntime(687): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.com/com.example.com.MainActivity}: java.lang.ClassNotFoundException: com.example.com.MainActivity in loader dalvik.system.PathClassLoader[/data/app/com.example.com-2.apk]
Manifest
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.com"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="18" />
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<application
android:allowBackup="true"
android:icon="#drawable/icon"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.example.com.MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>

If you have not added these two functions in your code, then add it and try. It will work.
#Override
protected void onPostCreate(Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
// Sync the toggle state after onRestoreInstanceState has occurred.
mDrawerToggle.syncState();
}
#Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
// Pass any configuration change to the drawer toggls
mDrawerToggle.onConfigurationChanged(newConfig);
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// The action bar home/up action should open or close the drawer.
// ActionBarDrawerToggle will take care of this.
if (mDrawerToggle.onOptionsItemSelected(item)) {
return true;
}
return false;
}

We Keep Coding

Java is a programming language and computing platform first released by Sun Microsystems in 1995.

Problems while switching activity using intent - java

Related

Crashing app while using search bar in action bar in android. MainActivity is not able decide which one has to be executed first?

RuntimeException on newly created NavDrawer

Attempt to invoke virtual method 'void android.app.ActionBar.setDisplayHomeAsUpEnabled(boolean)' on a null object reference NullPointer [duplicate]

Android sliding menu using navigation drawer

mDrawer can't work on android >3

Categories

Resources