I created a Settings Activity with the Android Template.
First, everything worked fine, but now I wanted to get the String from the EditTextPreference. But when I started to run it, it crashed because of this error:
java.lang.ClassCastException: java.lang.Boolean cannot be cast to java.lang.String
I used the right Key and the getString Method.
Since that happened every time I want to open the Settings my app crashes and I get that Error:
2020-02-01 17:22:55.260 24468-24468/de.fabipfolix.vertretungsplan E/AndroidRuntime: FATAL EXCEPTION: main
Process: de.fabipfolix.vertretungsplan, PID: 24468
java.lang.ClassCastException: java.lang.Boolean cannot be cast to java.lang.String
at android.app.SharedPreferencesImpl.getString(SharedPreferencesImpl.java:288)
at androidx.preference.Preference.getPersistedString(Preference.java:1686)
at androidx.preference.EditTextPreference.onSetInitialValue(EditTextPreference.java:106)
at androidx.preference.Preference.onSetInitialValue(Preference.java:1614)
at androidx.preference.Preference.dispatchSetInitialValue(Preference.java:1587)
at androidx.preference.Preference.onAttachedToHierarchy(Preference.java:1311)
at androidx.preference.Preference.onAttachedToHierarchy(Preference.java:1326)
at androidx.preference.PreferenceGroup.addPreference(PreferenceGroup.java:249)
at androidx.preference.PreferenceGroup.addItemFromInflater(PreferenceGroup.java:170)
at androidx.preference.PreferenceInflater.rInflate(PreferenceInflater.java:345)
at androidx.preference.PreferenceInflater.rInflate(PreferenceInflater.java:346)
at androidx.preference.PreferenceInflater.inflate(PreferenceInflater.java:157)
at androidx.preference.PreferenceInflater.inflate(PreferenceInflater.java:109)
at androidx.preference.PreferenceManager.inflateFromResource(PreferenceManager.java:216)
at androidx.preference.PreferenceFragmentCompat.setPreferencesFromResource(PreferenceFragmentCompat.java:377)
at de.fabipfolix.vertretungsplan.SettingsActivity$SettingsFragment.onCreatePreferences(SettingsActivity.java:42)
at androidx.preference.PreferenceFragmentCompat.onCreate(PreferenceFragmentCompat.java:160)
at androidx.fragment.app.Fragment.performCreate(Fragment.java:2586)
at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:838)
at androidx.fragment.app.FragmentTransition.addToFirstInLastOut(FragmentTransition.java:1197)
at androidx.fragment.app.FragmentTransition.calculateFragments(FragmentTransition.java:1080)
at androidx.fragment.app.FragmentTransition.startTransitions(FragmentTransition.java:119)
at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManagerImpl.java:1866)
at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManagerImpl.java:1824)
at androidx.fragment.app.FragmentManagerImpl.execPendingActions(FragmentManagerImpl.java:1727)
at androidx.fragment.app.FragmentManagerImpl.dispatchStateChange(FragmentManagerImpl.java:2663)
at androidx.fragment.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManagerImpl.java:2613)
at androidx.fragment.app.FragmentController.dispatchActivityCreated(FragmentController.java:246)
at androidx.fragment.app.FragmentActivity.onStart(FragmentActivity.java:542)
at androidx.appcompat.app.AppCompatActivity.onStart(AppCompatActivity.java:201)
at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1425)
at android.app.Activity.performStart(Activity.java:7825)
at android.app.ActivityThread.handleStartActivity(ActivityThread.java:3294)
at android.app.servertransaction.TransactionExecutor.performLifecycleSequence(TransactionExecutor.java:221)
at android.app.servertransaction.TransactionExecutor.cycleToPath(TransactionExecutor.java:201)
at android.app.servertransaction.TransactionExecutor.executeLifecycleState(TransactionExecutor.java:173)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:97)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:214)
at android.app.ActivityThread.main(ActivityThread.java:7356)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
I already commented on everything I've done today and I have no idea what the problem is.
The Design Window of the XML file says that I have to put a boolean.
Does anyone know how to solve this?
Here are my files:
root_preferences.xml:
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">
<PreferenceCategory app:title="Login Daten">
<EditTextPreference
android:ems="10"
android:inputType="text"
android:key="pref_username"
android:title="BenutzernameEditText"
app:title="Benutzername"
app:useSimpleSummaryProvider="true" />
<EditTextPreference
android:dialogTitle="Passwort"
android:inputType="text"
android:key="pref_password"
android:title="Passwort" />
</PreferenceCategory>
<PreferenceCategory app:title="Benachrichtigungen">
<SwitchPreference
android:defaultValue="true"
android:key="switchNotifications"
android:summary="#string/summarySwitchNotifications"
android:title="NotificationSwitch" />
</PreferenceCategory>
<PreferenceCategory app:title="Hintergrundaktivität">
</PreferenceCategory>
<PreferenceCategory app:title="Oberstufe">
<SwitchPreference
android:contentDescription="Kursbezeichnungen mit Komma trennen"
android:defaultValue="false"
android:key="switchKurse"
android:title="Kurse filtern" />
<EditTextPreference
android:dialogMessage="Kursnamen mit Komma trennen "
android:key="pref_kurse"
android:summary="Kursnamen mit Komma trennen "
android:title="Kursbezeichnungen"
android:inputType="text"
app:dialogTitle="Kursbezeichnungen" />
</PreferenceCategory>
MainActivity:
public class MainActivity extends AppCompatActivity {
FloatingActionButton fabRefresh;
RecyclerView recyclerView;
RecyclerView.Adapter adapter;
RecyclerView.LayoutManager layoutManager;
ArrayList<Vertretungsstunde> vertretungen;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
SharedPreferences sharedPref =PreferenceManager.getDefaultSharedPreferences(this);
Boolean notifications = sharedPref.getBoolean(SettingsActivity.KEY_PREF_NOTIFICATIONS_SWITCH, false);
String username = sharedPref.getString(SettingsActivity.KEY_PREF_USERNAME_TEXT, "");
ArrayList<Vertretungsstunde> list = ...;
//RECYCLERVIEW
recyclerView = findViewById(R.id.rv_VertretungenHeute);
recyclerView.setHasFixedSize(false);
layoutManager = new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false);
recyclerView.setLayoutManager(layoutManager);
((SimpleItemAnimator) recyclerView.getItemAnimator()).setSupportsChangeAnimations(false);
adapter = new VertretungsAdapter(this, list);
recyclerView.setAdapter(adapter);
//TOOLBAR
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
//REFRESH BUTTON
fabRefresh = findViewById(R.id.fabRefresh);
fabRefresh.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) { //FABRefresh OnClickListener
Toast.makeText(MainActivity.this, "Refreshing...", Toast.LENGTH_SHORT).show();
//...
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
Intent intent = new Intent(MainActivity.this, de.fabipfolix.vertretungsplan.SettingsActivity.class);
startActivity(intent);
return true;
}
return super.onOptionsItemSelected(item);
}
}
SettingsActivity:
public class SettingsActivity extends AppCompatActivity {
public static final String KEY_PREF_NOTIFICATIONS_SWITCH = "switchNotifications";
public static final String KEY_PREF_FILTER_SWITCH = "switchKurse";
public static final String KEY_PREF_KURSE_TEXT ="pref_kurse";
public static final String KEY_PREF_PASSWORD_TEXT = "pref_password";
public static final String KEY_PREF_USERNAME_TEXT = "pref_username";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.settings_activity);
getSupportFragmentManager()
.beginTransaction()
.replace(R.id.settings, new SettingsFragment())
.commit();
ActionBar actionBar = getSupportActionBar();
if (actionBar != null) {
actionBar.setDisplayHomeAsUpEnabled(true);
}
}
public static class SettingsFragment extends PreferenceFragmentCompat {
#Override
public void onCreatePreferences(Bundle savedInstanceState, String rootKey) {
setPreferencesFromResource(R.xml.root_preferences, rootKey);
}
}
}
Based on the comments:
You probably had previous saved data that could be breaking the current implementation. Cleaning storage should do it if that´s the case
Related
So,im trying to call some methods of an extended fragment class into mainActivity and somehow i cant get the variable to reference the actual fragment.
It says im referencing a null object when im calling the frag.method() line.
Is it because of wrong id in findFragmentByid() inside of the onCreate() in mainActivity?
Ive tried using the id of the linear and constraint layout ('yes' and 'paint'),still get the error.
Main activity
public class MainActivity extends AppCompatActivity {
public ViewGroup.LayoutParams params;
private Path path=new Path();
private Paint brush = new Paint();
private PaintView paintView;
FirstFragment frag=new FirstFragment();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
frag = (FirstFragment) getSupportFragmentManager().findFragmentById(R.id.paint);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar2);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayShowTitleEnabled(false);
toolbar.setMinimumWidth(20);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
switch (id){
case R.id.eraser:
frag.eraser();
return true;
case R.id.brush:
frag.brush();
return true;
}
return super.onOptionsItemSelected(item);
}
}
FirstFragment
public class FirstFragment extends Fragment {
public FirstFragment() {}
private PaintView paintView;
#Override
public View onCreateView(
LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState
) {
View rootView=inflater.inflate(R.layout.fragment_first,container,false);
LinearLayout Rl= (LinearLayout) rootView.findViewById(R.id.paint);
paintView=new PaintView(getActivity());
Rl.addView(paintView);
// Inflate the layout for this fragment
return rootView;
}
public void onViewCreated(#NonNull View view, Bundle savedInstanceState) {
paintView.brush();
super.onViewCreated(view, savedInstanceState);
/*
view.findViewById(R.id.button_first).setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
NavHostFragment.findNavController(FirstFragment.this)
.navigate(R.id.action_FirstFragment_to_SecondFragment);
}
});
*/
}
public void eraser()
{
paintView.eraser();
}
public void brush(){
paintView.brush();
}
}
first_fragment.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/yes"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".FirstFragment" >
<LinearLayout
android:id="#+id/paint"
android:layout_width="409dp"
android:layout_height="0dp"
android:layout_marginStart="1dp"
android:layout_marginTop="1dp"
android:layout_marginEnd="1dp"
android:orientation="horizontal"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"></LinearLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
Error
Process: com.example.myapplication, PID: 29743
java.lang.NullPointerException: Attempt to invoke virtual method 'void com.example.myapplication.FirstFragment.eraser()' on a null object reference
at com.example.myapplication.MainActivity.onOptionsItemSelected(MainActivity.java:50)
at android.app.Activity.onMenuItemSelected(Activity.java:4137)
at androidx.fragment.app.FragmentActivity.onMenuItemSelected(FragmentActivity.java:436)
at androidx.appcompat.app.AppCompatActivity.onMenuItemSelected(AppCompatActivity.java:196)
at androidx.appcompat.view.WindowCallbackWrapper.onMenuItemSelected(WindowCallbackWrapper.java:109)
at androidx.appcompat.view.WindowCallbackWrapper.onMenuItemSelected(WindowCallbackWrapper.java:109)
at androidx.appcompat.app.ToolbarActionBar$2.onMenuItemClick(ToolbarActionBar.java:64)
at androidx.appcompat.widget.Toolbar$1.onMenuItemClick(Toolbar.java:204)
at androidx.appcompat.widget.ActionMenuView$MenuBuilderCallback.onMenuItemSelected(ActionMenuView.java:781)
at androidx.appcompat.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:840)
at androidx.appcompat.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:158)
at androidx.appcompat.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:991)
at androidx.appcompat.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:981)
at androidx.appcompat.widget.ActionMenuView.invokeItem(ActionMenuView.java:625)
at androidx.appcompat.view.menu.ActionMenuItemView.onClick(ActionMenuItemView.java:151)
at android.view.View.performClick(View.java:7125)
at android.view.View.performClickInternal(View.java:7102)
at android.view.View.access$3500(View.java:801)
at android.view.View$PerformClick.run(View.java:27336)
at android.os.Handler.handleCallback(Handler.java:883)
at android.os.Handler.dispatchMessage(Handler.java:100)
at android.os.Looper.loop(Looper.java:214)
at android.app.ActivityThread.main(ActivityThread.java:7356)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
29743-29743/com.example.myapplication I/Process: Sending signal. PID: 29743 SIG: 9
Welp,the problem was caused by the fact that there was no fragment in the respective layout since the layout(yes,paint) was INSIDE the fragment i was trying to call,so basically id mismatch.Stupid me.
I have created a project int activity_main and want to add a Navigation drawer to it.
I have gone into the java folder. Right click > new > Actvity > Navigation Drawer activity.
Note: I DON't have an action bar, to create the menu button(3 stacked lines)
Now I don't know how to actually open the navigation drawer over activity_main, without the app crashing.
Thanks.
I've tried doing an on click listener with a button which has
the drawer layout defined as dl (DrawerLayout dl = (DrawerLayout)findviewbyIOd(R.id.Drawer_layout))
and have done
dl.openDrawer(Gravity.LEFT);
have tried putting the code from the NavDrawer activity into the activity_main, but app won't start.
public class MainActivity extends AppCompatActivity implements CompoundButton.OnCheckedChangeListener {
Switch OnOff;
EditText editText;
int NumberPicked;
int NumberPicked2;
private DrawerLayout dl;
private ActionBarDrawerToggle abdt;
Values[] troughvals = new Values[8];
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
BobbleSelector BS = new BobbleSelector();
final DrawerLayout dl = (DrawerLayout)findViewById(R.id.dl);
Button btnChange = (Button) findViewById(R.id.btnChange);
Switch OnOff = (Switch) findViewById(R.id.OnOff);
NumberPicker numberPicker2 = findViewById(R.id.numberPicker2);
NumberPicker numberPicker = findViewById(R.id.numberPicker);
numberPicker.setMinValue(00);
numberPicker2.setMinValue(00);
numberPicker2.setMaxValue(23);
numberPicker.setMaxValue(23);
btnChange.setOnClickListener( new View.OnClickListener(){
public void onClick(View v){
dl.openDrawer(Gravity.LEFT);
}
});
OnOff.setTextOff("On");
OnOff.setTextOn("Off");
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
return abdt.onOptionsItemSelected(item) || super.onOptionsItemSelected(item);
}
public void handleSwitchClick(View view) {
Switch s = (Switch) view;
boolean isChecked = s.isChecked();
}
#Override
public void onCheckedChanged(CompoundButton compoundButton, boolean isChecked){
switch (compoundButton.getId()){
case R.id.OnOff:
break;
}
}
}
Note: have disabled fab, because it could not be found in my project.
I have created a custom Menu for the Navigation Drawer
public class BobbleSelector extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_bobble_selector);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// Button fab = findViewById(R.id.btnChange);
// fab.setOnClickListener(new View.OnClickListener() {
// #Override
// public void onClick(View view) {
// Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
// .setAction("Action", null).show();
// }
// });
DrawerLayout drawer = findViewById(R.id.dl);
NavigationView navigationView = findViewById(R.id.nav_view);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.addDrawerListener(toggle);
toggle.syncState();
navigationView.setNavigationItemSelectedListener(this);
}
#Override
public void onBackPressed() {
DrawerLayout drawer = findViewById(R.id.dl);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.bobble_selector, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
#SuppressWarnings("StatementWithEmptyBody")
#Override
public boolean onNavigationItemSelected(MenuItem item) {
// Handle navigation view item clicks here.
int id = item.getItemId();
DrawerLayout drawer = findViewById(R.id.dl);
drawer.closeDrawer(GravityCompat.START);
return true;
}
}
Drawer Layout
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/dl"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:openDrawer="start">
<include
layout="#layout/app_bar_bobble_selector"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<android.support.design.widget.NavigationView
android:id="#+id/nav_view"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
android:fitsSystemWindows="true"
app:headerLayout="#layout/nav_header_bobble_selector"
app:menu="#menu/nav_menu" />
</android.support.v4.widget.DrawerLayout>
From Logcat
2019-06-02 13:13:08.195 12745-12745/com.example.mytest E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.mytest, PID: 12745
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v4.widget.DrawerLayout.openDrawer(int)' on a null object reference
at com.example.mytest.MainActivity$1.onClick(MainActivity.java:49)
at android.view.View.performClick(View.java:6294)
at android.view.View$PerformClick.run(View.java:24770)
at android.os.Handler.handleCallback(Handler.java:790)
at android.os.Handler.dispatchMessage(Handler.java:99)
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:440)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
Expected to open drawer with the changebutton.openDrawer(Gravity.Left) But crashes the app.
Found I needed to move the code relating to the nav bar to the bottom of OnCreate and set the "SetContentView()" to be the layout for the Navigation bar.
Then it worked perfectly.
Before
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button btn = findViewById(R.id.btnChange);
drawer = findViewById(R.id.dl);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this,drawer, R.string.navigation_drawer_open,R.string.navigation_drawer_close);
drawer.addDrawerListener(toggle);
toggle.syncState();
//Not nav
Switch OnOff = (Switch) findViewById(R.id.OnOff);
NumberPicker numberPicker2 = findViewById(R.id.numberPicker2);
NumberPicker numberPicker = findViewById(R.id.numberPicker);
numberPicker.setMinValue(00);
numberPicker2.setMinValue(00);
numberPicker2.setMaxValue(23);
numberPicker.setMaxValue(23);
OnOff.setTextOff("On");
OnOff.setTextOn("Off");
//not nav
}
After
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button btn = findViewById(R.id.btnChange);
//Not nav
Switch OnOff = (Switch) findViewById(R.id.OnOff);
NumberPicker numberPicker2 = findViewById(R.id.numberPicker2);
NumberPicker numberPicker = findViewById(R.id.numberPicker);
numberPicker.setMinValue(00);
numberPicker2.setMinValue(00);
numberPicker2.setMaxValue(23);
numberPicker.setMaxValue(23);
OnOff.setTextOff("On");
OnOff.setTextOn("Off");
//not nav
setContentView(R.layout.activity_bobble_selector);
drawer = findViewById(R.id.dl);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this,drawer, R.string.navigation_drawer_open,R.string.navigation_drawer_close);
assert drawer != null;
drawer.addDrawerListener(toggle);
toggle.syncState();
}
I am trying to set up the Android Nav Drawer with an action bar. I am having difficulty setting the icon for the Nav Drawer and generating all of the list items as well. Below is my code, I am currently generating a NullPointer Exception:
Crash:
--------- beginning of crash
04-20 18:02:03.690 13170-13170/com.sourcey.materialloginexample E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.sourcey.materialloginexample, PID: 13170
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.sourcey.materialloginexample/com.troychuinard.fanpolls.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:2325)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
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:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setDisplayHomeAsUpEnabled(boolean)' on a null object reference
at com.troychuinard.fanpolls.MainActivity.onCreate(MainActivity.java:71)
at android.app.Activity.performCreate(Activity.java:5990)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
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:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
MainActivity:
public class MainActivity extends AppCompatActivity implements HomePollsFragment.OnFragmentInteractionListener {
private Toolbar toolbar;
private Firebase mPollsRef;
private ViewPager mPager;
private ScreenSlidePagerAdapter mPagerAdapter;
private DateFormat mDateFormat;
private Date mDate;
private String mCurrentDateString;
private ValueEventListener v;
private String[] mPlanetTitles;
private DrawerLayout mDrawerLayout;
private ListView mDrawerList;
private ActionBarDrawerToggle mDrawerToggle;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
toolbar = (Toolbar) findViewById(R.id.action_tool_bar);
setSupportActionBar(toolbar);
Firebase.setAndroidContext(this);
mPollsRef = FirebaseUtil.FIREBASE.child("Polls");
mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
mDrawerToggle = new ActionBarDrawerToggle(
this, /* host Activity */
mDrawerLayout, /* DrawerLayout object */
toolbar, /* nav drawer icon to replace 'Up' caret */
R.string.drawer_open, /* "open drawer" description */
R.string.drawer_close /* "close drawer" description */) {
};
getActionBar().setDisplayHomeAsUpEnabled(true);
getActionBar().setHomeButtonEnabled(true);
mDrawerList = (ListView) findViewById(R.id.left_drawer);
ArrayList<String> drawerTitleArray = new ArrayList<>();
drawerTitleArray.add(0, "TEST");
drawerTitleArray.add(1, "TEST 1");
// Set the adapter for the list view
mDrawerList.setAdapter(new ArrayAdapter<String>(this,
R.layout.drawer_list_item, drawerTitleArray));
// TODO: Add Fragment Code to check if savedInstanceState == null; add at Activity Level?
// Check that the activity is using the layout version with
// the fragment_container FrameLayout
//set up viewpager for current day
mPager = (ViewPager) findViewById(R.id.home_polls_viewpager_fragment_container);
mPagerAdapter = new ScreenSlidePagerAdapter(getSupportFragmentManager());
mPager.setAdapter(mPagerAdapter);
//get current date to apply to Viewpager
mDateFormat = new SimpleDateFormat("MM-dd-yyyy");
mDate = new Date();
mCurrentDateString = mDateFormat.format(mDate);
// TODO: Checkn if AuthStateListenerNecessary
//Determine whether necessary to use an AuthStateListener here
// mUserRef.addAuthStateListener(new Firebase.AuthStateListener() {
// #Override
// public void onAuthStateChanged(AuthData authData) {
// if (authData == null) {
// Intent backToSignIn = new Intent(getApplication(), SignupActivity.class);
// startActivity(backToSignIn);
// finish();
// }
// }
// })
}
#Override
protected void onStart() {
super.onStart();
v = new ValueEventListener() {
//testing methodology of adding children
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
int pollsAvailable = (int) dataSnapshot.child(mCurrentDateString).getChildrenCount();
mPagerAdapter.setPollsAvailable(pollsAvailable);
Log.i("TAG", "There are " + String.valueOf(pollsAvailable) + " children in today's poll count.");
}
#Override
public void onCancelled(FirebaseError firebaseError) {
}
};
mPollsRef.addValueEventListener(v);
}
#Override
protected void onStop() {
super.onStop();
mPollsRef.removeEventListener(v);
}
#Override
public void onFragmentInteraction(Uri uri) {
}
class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter {
private int pollsAvailable = 0;
//fragment adapter constructor
public ScreenSlidePagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
return HomePollsFragment.newInstance(position);
}
#Override
public int getCount() {
return pollsAvailable;
}
public void setPollsAvailable(int pollsAvailable) {
this.pollsAvailable = pollsAvailable;
this.notifyDataSetChanged();
}
}
#Override
public void onBackPressed() {
super.onBackPressed();
if (mPager.getCurrentItem() == 0) {
// If the user is currently looking at the first step, allow the system to handle the
// Back button. This calls finish() on this activity and pops the back stack.
super.onBackPressed();
} else {
// Otherwise, select the previous step.
mPager.setCurrentItem(mPager.getCurrentItem() - 1);
}
}
}
XML:
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<LinearLayout
android:id="#+id/content_frame"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<android.support.v7.widget.Toolbar
android:id="#+id/action_tool_bar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#color/actionRed">
</android.support.v7.widget.Toolbar>
<android.support.v4.view.ViewPager
android:id="#+id/home_polls_viewpager_fragment_container"
android:layout_width="match_parent"
android:layout_height="match_parent">
</android.support.v4.view.ViewPager>
</LinearLayout>
<!-- The navigation drawer -->
<ListView
android:id="#+id/left_drawer"
android:layout_width="240dp"
android:layout_height="match_parent"
android:layout_gravity="start"
android:background="#111"
android:choiceMode="singleChoice"
android:divider="#android:color/transparent"
android:dividerHeight="0dp" />
</android.support.v4.widget.DrawerLayout>
I do it like this:
android.support.v7.app.ActionBar actionBar = getSupportActionBar();
if(actionBar != null){
actionBar.setDisplayHomeAsUpEnabled(true);
actionBar.setHomeButtonEnabled(true);
}
This should solve the java.lang.NullPointerException.
"and generating all of the list items as well"
I cant see whats the problem here. Could you explain it a little bit?
The icon - Three horizontal lines in closed mode, a back arrow in opened mode with a nice smoot animation:
drawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
drawerToggle = new ActionBarDrawerToggle(
this, /* host Activity */
drawerLayout, /* DrawerLayout object */
toolbar, /* nav drawer icon to replace 'Up' caret */
R.string.nav, /* "open drawer" description */
R.string.nav /* "close drawer" description */
) {
/** Called when a drawer has settled in a completely closed state. */
public void onDrawerClosed(View view) {
super.onDrawerClosed(view);
if(extra == null){
toolbar.setTitle(title);
}else{
toolbar.setTitle(title + " - " + extra);
}
isOpen = false;
}
/** Called when a drawer has settled in a completely open state. */
public void onDrawerOpened(View drawerView) {
super.onDrawerOpened(drawerView);
actionBar.setTitle(R.string.nav);
isNavReady = true;
isOpen = true;
}
};
drawerLayout.addDrawerListener(drawerToggle);
#Override
public boolean onOptionsItemSelected(MenuItem item){
return drawerToggle.onOptionsItemSelected(item) || super.onOptionsItemSelected(item);
}
#Override
protected void onPostCreate(Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
// Sync the toggle state after onRestoreInstanceState has occurred.
drawerToggle.syncState();
}
#Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
drawerToggle.onConfigurationChanged(newConfig);
}
I am working on an Android project in which I would like to add Drawer functionality, for which I already have classes and all ready.
THe problem is the Drawer code works by extends or extending the class which wants to add a drawer, and similarly my GoogleMaps code works in the same way. But because of Multiple-inheritance, I cannot extend 2 classes.
What should I do?
Google-maps code :
public class MapsActivity extends FragmentActivity {
GoogleMap googleMap;
SharedPreferences sharedPreferences;
int locationCount = 0;
private RestaurantServiceImpl restaurantService = new RestaurantServiceImpl();
List<RestRestaurant> restRestaurantList = new ArrayList<>();
GPSTracker gps;
double longitude, latitude;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.mapsact);
SupportMapFragment fm = (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map);
// Getting GoogleMap object from the fragment
googleMap = fm.getMap();
// Enabling MyLocation Layer of Google Map
googleMap.setMyLocationEnabled(true);
// Opening the sharedPreferences object
sharedPreferences = getSharedPreferences("location", 0);
// Getting number of locations already stored
locationCount = sharedPreferences.getInt("locationCount", 0);
// Getting stored zoom level if exists else return 0
String zoom = sharedPreferences.getString("zoom", "12");
gps = new GPSTracker(MapsActivity.this);
if (gps.canGetLocation()) {
longitude = gps.getLongitude();
latitude = gps.getLatitude();
restRestaurantList = this.restaurantService.getRestaurantsByLocation(longitude,latitude);
double lat=0, longi=0;
for(RestRestaurant restRestaurant : restRestaurantList){
drawMarker(new LatLng(restRestaurant.getLatitude(),restRestaurant.getLongitude()), restRestaurant.getRestaurantName(), restRestaurant.getRestaurantId());
lat = restRestaurant.getLatitude();
longi = restRestaurant.getLongitude();
}
googleMap.moveCamera(CameraUpdateFactory.newLatLng(new LatLng(lat,longi)));
// Setting the zoom level in the map on last position is clicked
googleMap.animateCamera(CameraUpdateFactory.zoomTo(Float.parseFloat(zoom)));
} else {
gps.showSettingsAlert();
}
googleMap.setOnMarkerClickListener(new GoogleMap.OnMarkerClickListener() {
#Override
public boolean onMarkerClick(Marker marker) {
int restoId = Integer.valueOf(marker.getSnippet());
Intent intent = new Intent(MapsActivity.this, MenuCardList.class);
intent.putExtra("restaurantid", restoId);
startActivity(intent);
finish();
return true;
}
});
}
This class I need to extend to add a drawer :
public class DrawerLoader extends Activity {
private DrawerLayout mDrawerLayout;
private ListView mDrawerList;
private ActionBarDrawerToggle mDrawerToggle;
// nav drawer title
private CharSequence mDrawerTitle;
// used to store app title
private CharSequence mTitle;
private ArrayList<DrawerModel> navDrawerItems;
private DrawerListAdapter adapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.drawerlayout);
}
public void set(String[] navMenuTitles, TypedArray navMenuIcons) {
mTitle = mDrawerTitle = getTitle();
navMenuTitles = getResources().getStringArray(R.array.nav_drawer_items);
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<DrawerModel>();
If any more information is required, kindly let me know.
Ignoring all your work regarding a navigation drawer, this would be my preferred solution, since There is no need for a extra Fragment, List filling, new classes....
1, Create a nav_menu.xml (in menues folder):
<menu xmlns:android="http://schemas.android.com/apk/res/android">
<group
android:checkableBehavior="single">
<item
android:id="#+id/drawer_home"
android:checked="true"
android:icon="#drawable/ic_home_black_24dp"
android:title="Home"/>
<item
android:id="#+id/drawer_favourite"
android:icon="#drawable/ic_favorite_black_24dp"
android:title="Favourites"/>
<item
android:id="#+id/drawer_settings"
android:icon="#drawable/ic_settings_black_24dp"
android:title="Settings"/>
</group>
2, Wrap your activites layout with a DrawerLayout:
<android.support.v4.widget.DrawerLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<!-- Your activity layout here-->
<android.support.design.widget.NavigationView
android:id="#+id/navigation_view"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
app:headerLayout="#layout/drawer_header"
app:menu="#menu/nav_menu"/>
</android.support.v4.widget.DrawerLayout>
3, Update your activities java code:
//If you have a toolbar (recommended!)
final Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
final ActionBar actionBar = getSupportActionBar();
if (actionBar != null) {
actionBar.setDisplayHomeAsUpEnabled(true);
}
//and finally the Navigation View Code:
final NavigationView navigation = (NavigationView) findViewById(R.id.navigation);
navigation.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
#Override
public boolean onNavigationItemSelected(MenuItem menuItem) {
navigation.setCheckedItem(menuItem.getItemId());
drawerLayout.closeDrawers();
switch (menuItem.getItemId()) {
case R.id.drawer_home:
//open fragment home
return true;
case R.id.drawer_favourite:
//open fragment favourite
return true;
case R.id.nav_drawer_channels:
showFragment(2);
return true;
case R.id.drawer_settings:
//open settings
return true;
}
return false;
}
});
DrawerLayout drawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
ActionBarDrawerToggle drawerToggle = new ActionBarDrawerToggle(
this,
drawerLayout,
toolbar,
R.string.drawer_open, //simply a String "open"
R.string.drawer_close) { //simply a String "close"
public void onDrawerClosed(View view) {
super.onDrawerOpened(drawerLayout);
drawerToggle.syncState();
}
public void onDrawerOpened(View drawerView) {
super.onDrawerClosed(drawerLayout);
drawerToggle.syncState();
}
};
drawerLayout.setDrawerListener(drawerToggle);
drawerToggle.syncState();
//And, last but not least, open the drawer with a Click on 'home'
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
drawerLayout.openDrawer(GravityCompat.START);
return true;
}
return super.onOptionsItemSelected(item);
}
And you are done! No messing with extra fragment, unnecessary and messy code.
I am trying to implement a navigation drawer in a BaseActivity, that shows different options depending on the activity that is currently showing. For that, I developed a BaseActivity, that implements the navigation drawer, and decides what to show, depending on the activity that is currently showing. The purpose of this, is to make all other activities that need to use the navigation drawer, expand the BaseActivity.
The following code, shows no errors, but the navigation drawer shows itself completely empty, and does not show when I click the 'home' button, neither the 'menu' button, a functionality that I implemented with the 'onKeyDown' method. It just shows, when I use the following gesture: move the finger from the left to the right in the left side of the screen.
When I do the same in each class I need, instead of using a BaseActivity, everything works perfeclty fine.
I have been trying this for days now and I still do not understand why, the content of the navigation drawer is still not showing. I would appreciate some help please. Thanks in advance.
Here, the core classes of the problem:
BaseActivity.java
public abstract class BaseActivity extends ActionBarActivity
{
public DrawerLayout drawerLayout = null;
public ActionBarDrawerToggle drawerToggle = null;
public Activity currentActivity = null;
public ArrayList<Item> navDrawerItems = new ArrayList<Item>();
public ItemListAdapter adapter = null;
public ListView drawerList = null;
int id = 0;
protected void onCreate(Bundle savedInstanceState, int resLayoutID)
{
super.onCreate(savedInstanceState);
setContentView(resLayoutID);
currentActivity = this;
drawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
drawerToggle = new ActionBarDrawerToggle(currentActivity,
drawerLayout,
R.drawable.ic_drawer,
R.string.open_menu,
R.string.close_menu)
{
public void onDrawerClosed(View view)
{
Log.e("", "Close drawer");
getSupportActionBar().setTitle(getTitle());
ActivityCompat.invalidateOptionsMenu(currentActivity);
}
public void onDrawerOpened(View drawerView)
{
Log.e("", "Open drawer");
getSupportActionBar().setTitle(getTitle());
ActivityCompat.invalidateOptionsMenu(currentActivity);
}
};
drawerLayout.setDrawerListener(drawerToggle);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setHomeButtonEnabled(true);
// Populate navigation drawer depending on the activity
// that is currently showing.
if (this.getClass().getSimpleName().equals("Z"))
setUpNavigationForZActivity();
}
private void setUpNavigationForZActivity()
{
Log.e("", "In setUpNavigationForZActivity");
// Prepare list items.
id = R.string.title_activity_A;
navDrawerItems.add(new NavigationDrawerItem(getString(id), Utils.activityIcon().get(id)));
id = R.string.title_activity_B;
navDrawerItems.add(new NavigationDrawerItem(getString(id), Utils.activityIcon().get(id)));
// Populate view.
drawerList = (ListView) findViewById(R.id.left_menu);
adapter = new ItemListAdapter(currentActivity, navDrawerItems;
drawerList.setAdapter(adapter);
drawerList.setOnItemClickListener(new OnItemClickListener()
{
public void onItemClick(AdapterView<?> parent, View view, int position,
long id)
{
Intent intent = null;
switch(position)
{
case 0:
intent = new Intent(currentActivity, A.class);
startActivity(intent)
break;
case 1:
intent = new Intent(currentActivity, B.class);
startActivity(intent)
break;
default:
}
}
});
}
#Override
public boolean onOptionsItemSelected(MenuItem item)
{
if (drawerToggle.onOptionsItemSelected(item))
return true;
return super.onOptionsItemSelected(item);
}
#Override
protected void onPostCreate(Bundle savedInstanceState)
{
super.onPostCreate(savedInstanceState);
drawerToggle.syncState();
}
#Override
public void onConfigurationChanged(Configuration newConfig)
{
super.onConfigurationChanged(newConfig);
drawerToggle.onConfigurationChanged(newConfig);
}
#Override
public boolean onKeyDown(int keyCode, KeyEvent e)
{
Log.e("", "onKeyDown");
if (keyCode == KeyEvent.KEYCODE_MENU)
{
if(!drawerLayout.isDrawerOpen(Gravity.LEFT))
drawerLayout.openDrawer(Gravity.LEFT);
else
drawerLayout.closeDrawer(Gravity.LEFT);
}
return super.onKeyDown(keyCode, e);
}
}
Z.java
public class Z extends BaseActivity
{
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState, R.layout.Z);
setContentView(R.layout.Z);
//Other things to do...
}
}
Z.xml
<android.support.v4.widget.DrawerLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<!-- Main content view -->
<ScrollView
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:fillViewport="true" >
// Other layout and views configurations...
</ScrollView>
<!-- Navigation drawer -->
<ListView
android:id="#+id/left_menu"
android:layout_width="240dp"
android:layout_height="match_parent"
android:layout_gravity="start"
android:background="#color/gray_7_5"
android:choiceMode="singleChoice" />
</android.support.v4.widget.DrawerLayout>
I do not exactly know why you would want to implement it that way but if you still want to do it this way i would suggest making your navdrawer use a listview with an adapter to draw items from an array and then have your base activity have a getData() call that you can override in your derived activities that will supply the data that the Adapter so that the listview will then draw the appropriate items in the navdrawer. You will then have to implement the onItemClick event for each listview per activity.