I know that this is question had been asked several time, but I saw that the answer always change in relation to the code.
So, I have GameActivity that retrieve informations from a database in the global "info" variable, that is a String[].
Next I need to replace the current fragment with another fragment in relation to the button pressed (see methods "trueAnswer" and "falseAnswer"), and set two TextViews of that new fragment with the informations retrieved in the "info" string array.
The problem is that I'm able to set the informations the first time, in the first fragment in the method onStart() when the activity is created, but then seems like the "info" array is empty, because the "if" in the methods "trueAnswer" and "falseAnswer" doesn't works, and when I try to set the TextViews in the new fragment with the method "changeText(String, String)", the app crashes and return a NullPointerExeption.
I can't really see where is the error in the code, so I post here my methods and the logCat, hoping that may help you too.
GameActivity:
import java.io.IOException;
import android.content.SharedPreferences;
import android.database.SQLException;
import android.graphics.Color;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.FrameLayout;
import android.widget.TextView;
import android.widget.Toast;
public class GameActivity extends ActionBarActivity {
public long n = 0;
public String[] info = new String[3];
DataBase myDbHelper = new DataBase(this);
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_game);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.replace(R.id.container, new PlaceholderFragment()).commit();
}
}
public void randomize(){
n = Math.round((Math.random()*3)+1);
}
public String[] getDatabaseInfo(){
myDbHelper.refresh();
try {
myDbHelper.createDataBase();
} catch (IOException ioe) {
throw new Error("NON HO CARICATO IL DATABASE TI PREGO SCUSAMI");
}
try {
myDbHelper.openDataBase();
}catch(SQLException sqle){
throw sqle;
}
return info = myDbHelper.getQuestion(n);
}
#Override
public void onStart(){
super.onStart();
randomize();
getDatabaseInfo();
TextView d = (TextView)findViewById(R.id.question);
d.setText(info[1]);
}
#Override
public void onResume(){
super.onResume();
// Controlla qual e il colore di sfondo nei settings e lo applica
FrameLayout ll = (FrameLayout)findViewById(R.id.container);
SharedPreferences sharedPref = PreferenceManager.getDefaultSharedPreferences(this);
int bgc = Color.parseColor(sharedPref.getString("background_color", "#000000"));
if(bgc == Color.BLACK){
TextView myTextView = (TextView)findViewById(R.id.question);
TextView r = (TextView)findViewById(R.id.answer);
myTextView.setTextColor(Color.WHITE);
r.setTextColor(Color.GRAY);
}
ll.setBackgroundColor(bgc);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.game, 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();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
public void trueAnswer(View view){
if(info[2] == "1"){
// Create new fragment and transaction
FragmentCorrect newFragment = new FragmentCorrect();
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
// Replace whatever is in the fragment_container view with this fragment,
// and add the transaction to the back stack
transaction.replace(R.id.container, newFragment);
// Commit the transaction
transaction.commit();
newFragment.changeText(info[1], info[0]);
}else{
// Create new fragment and transaction
FragmentWrong newFragment = new FragmentWrong();
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
// Replace whatever is in the fragment_container view with this fragment,
// and add the transaction to the back stack
transaction.replace(R.id.container, newFragment);
// Commit the transaction
transaction.commit();
newFragment.changeText(info[1], info[0]);
}
}
public void falseAnswer(View view){
if(info[2] == "1"){
// Create new fragment and transaction
FragmentCorrect newFragment = new FragmentCorrect();
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
// Replace whatever is in the fragment_container view with this fragment,
// and add the transaction to the back stack
transaction.replace(R.id.container, newFragment);
// Commit the transaction
transaction.commit();
newFragment.changeText(info[1], info[0]);
}else{
// Create new fragment and transaction
FragmentWrong newFragment = new FragmentWrong();
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
// Replace whatever is in the fragment_container view with this fragment,
// and add the transaction to the back stack
transaction.replace(R.id.container, newFragment);
// Commit the transaction
transaction.commit();
newFragment.changeText(info[1], info[0]);
}
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_game, container,
false);
return rootView;
}
}
}
FragmentCorrect:
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
public class FragmentCorrect extends Fragment {
TextView questionTv, answerTv;
public FragmentCorrect() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_corretto, container,
false);
questionTv = (TextView)rootView.findViewById(R.id.question);
answerTv = (TextView)rootView.findViewById(R.id.answer);
return rootView;
}
public void changeText(String question, String answer){
questionTv.setText(question);
answerTv.setText(answer);
}
}
FragmentWrong:(same code as FragmentCorrect, but with a different fragment layout).
LogCat:
05-19 12:13:04.278: E/AndroidRuntime(16694): FATAL EXCEPTION: main
05-19 12:13:04.278: E/AndroidRuntime(16694): java.lang.IllegalStateException: Could not execute method of the activity
05-19 12:13:04.278: E/AndroidRuntime(16694): at android.view.View$1.onClick(View.java:3704)
05-19 12:13:04.278: E/AndroidRuntime(16694): at android.view.View.performClick(View.java:4232)
05-19 12:13:04.278: E/AndroidRuntime(16694): at android.view.View$PerformClick.run(View.java:17298)
05-19 12:13:04.278: E/AndroidRuntime(16694): at android.os.Handler.handleCallback(Handler.java:615)
05-19 12:13:04.278: E/AndroidRuntime(16694): at android.os.Handler.dispatchMessage(Handler.java:92)
05-19 12:13:04.278: E/AndroidRuntime(16694): at android.os.Looper.loop(Looper.java:137)
05-19 12:13:04.278: E/AndroidRuntime(16694): at android.app.ActivityThread.main(ActivityThread.java:4921)
05-19 12:13:04.278: E/AndroidRuntime(16694): at java.lang.reflect.Method.invokeNative(Native Method)
05-19 12:13:04.278: E/AndroidRuntime(16694): at java.lang.reflect.Method.invoke(Method.java:511)
05-19 12:13:04.278: E/AndroidRuntime(16694): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1027)
05-19 12:13:04.278: E/AndroidRuntime(16694): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:794)
05-19 12:13:04.278: E/AndroidRuntime(16694): at dalvik.system.NativeStart.main(Native Method)
05-19 12:13:04.278: E/AndroidRuntime(16694): Caused by: java.lang.reflect.InvocationTargetException
05-19 12:13:04.278: E/AndroidRuntime(16694): at java.lang.reflect.Method.invokeNative(Native Method)
05-19 12:13:04.278: E/AndroidRuntime(16694): at java.lang.reflect.Method.invoke(Method.java:511)
05-19 12:13:04.278: E/AndroidRuntime(16694): at android.view.View$1.onClick(View.java:3699)
05-19 12:13:04.278: E/AndroidRuntime(16694): ... 11 more
05-19 12:13:04.278: E/AndroidRuntime(16694): Caused by: java.lang.NullPointerException
05-19 12:13:04.278: E/AndroidRuntime(16694): at com.example.quizone_2.FragmentWrong.changeText(FragmentWrong.java:29)
05-19 12:13:04.278: E/AndroidRuntime(16694): at com.example.quizone_2.GameActivity.trueAnswer(GameActivity.java:151)
05-19 12:13:04.278: E/AndroidRuntime(16694): ... 14 more
05-19 12:13:06.403: I/Process(16694): Sending signal. PID: 16694 SIG: 9
Thank you very much in advance
You're creating a new fragment and immediately calling changeText() on it. The fragment transaction that creates the fragment view, calling the lifecycle callbacks such as onCreateView(), has not yet been run.
Consider passing arguments to your fragmens using a bundle and not call fragment methods directly outside fragment lifecycle.
You are calling
newFragment.changeText(info[1], info[0]);
too soon. You need to wait till the Fragment is attached to the Activity. Your views are null.
Also use .equalsto compare strings instead of == .
if(info[2].equals("1"))
Get to know Fragment lifecycle
http://developer.android.com/guide/components/fragments.html
Adding further to what laalto posted
Send data from activity to fragment in android
Related
I'm new in android development and I'm trying to build a kind of book listing kind of app for a project in my class. The prof's favorite motto is "whatever you don't know google it". That's not bad when you semi-know what to do but since we are learning java along with android development that's not helpful since java can seem a bit alien.
Anyways basing my app in a contact app this is how my MainActivity looks
//MainActivity.java
package com.iekproject.siegfried.libraryapp;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
public class MainActivity extends AppCompatActivity
implements LibraryFragment.LibraryFragmentListener, DetailFragment.DetailFragmentListener,
AddEditFragment.AddEditFragmentListener {
//key for storing a book's Uri in a Bundle passed to a fragment
public static final String BOOK_URI = "book_uri";
private LibraryFragment libraryFragment; //displays library aka book list
//displays LibraryFragment when MainActivity first loads
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
//if layout contains fragmentContainer, the phone layout is in use. Create and display
//a LibraryFragment
if (savedInstanceState == null && findViewById(R.id.fragmentContainer) != null) {
//create LibraryFragment
libraryFragment = new LibraryFragment();
//add the fragment to the FrameLayout
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.add(R.id.fragmentContainer, libraryFragment);
transaction.commit(); //displays LibraryFragment
}
else {
libraryFragment =
(LibraryFragment) getSupportFragmentManager().
findFragmentById(R.id.DetailFragment);
}
}
public boolean isExternalStorageReadable() {
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state) ||
Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) {
return true;
}
return false;
}
//displays DetailFragment for selected book
#Override
public void onBookSelected(Uri bookUri) {
getSupportFragmentManager().popBackStack();
displayBook(bookUri, R.id.rightPaneContainer);
}
//displays AddEditFragment to add a new book. Possibly what I'll also have to change to make it
//scan/update the book list
#Override
public void onAddBook() {
displayAddEditFragment(R.id.rightPaneContainer, null);
}
//displays a book
private void displayBook(Uri bookUri, int viewID) {
DetailFragment detailFragment = new DetailFragment();
//specify book's Uri as an argument to the DetailFragment
Bundle arguments = new Bundle();
arguments.putParcelable(BOOK_URI, bookUri);
detailFragment.setArguments(arguments);
//use a FragmentTransaction to display the DetailFragment
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(viewID, detailFragment);
transaction.addToBackStack(null);
transaction.commit(); //causes DetailFragment to display
}
//displays fragment for adding new or editing existing book
private void displayAddEditFragment(int viewID, Uri bookUri) {
AddEditFragment addEditFragment = new AddEditFragment();
//if editing existing book, provide bookUri as an argument
if (bookUri != null) {
Bundle arguments = new Bundle();
arguments.putParcelable(BOOK_URI, bookUri);
addEditFragment.setArguments(arguments);
}
//use a FragmentTransaction to display the AddEditFragment
FragmentTransaction transaction =
getSupportFragmentManager().beginTransaction();
transaction.replace(viewID, addEditFragment);
transaction.addToBackStack(null);
transaction.commit(); //causes AddEditFragment to display
}
//return to book list when displayed book deleted
#Override
public void onBookDeleted() {
//removes top of back stack
getSupportFragmentManager().popBackStack();
libraryFragment.updateLibrary(); //refresh book list
}
//displays the AddEditFragment to edit an existing book. Maybe it can be used as Move or sth
/*#Override
public void onEditBook(Uri bookUri) {
displayAddEditFragment(R.id.rightPaneContainer, bookUri);
}*/
//update GUI after the new book or updated book saved
#Override
public void onAddEditCompleted(Uri bookUri) {
//removes top of back stack
getSupportFragmentManager().popBackStack();
libraryFragment.updateLibrary(); //refresh book list
if (findViewById(R.id.fragmentContainer) == null){ //tablet
//removes top of back stack
getSupportFragmentManager().popBackStack();
//on tablet, displays the book that was just added or edited
displayBook(bookUri, R.id.rightPaneContainer);
}
}
}
and this is the logcat
04-12 16:14:38.807 5796-5796/? I/art: Not late-enabling -Xcheck:jni (already on)
04-12 16:14:38.808 5796-5796/? W/art: Unexpected CPU variant for X86 using defaults: x86
04-12 16:14:38.926 5796-5796/com.iekproject.siegfried.libraryapp W/System: ClassLoader referenced unknown path: /data/app/com.iekproject.siegfried.libraryapp-1/lib/x86
04-12 16:14:38.945 5796-5796/com.iekproject.siegfried.libraryapp I/InstantRun: starting instant run server: is main process
04-12 16:14:38.991 5796-5796/com.iekproject.siegfried.libraryapp W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter android.support.graphics.drawable.VectorDrawableCompat.updateTintFilter(android.graphics.PorterDuffColorFilter, android.content.res.ColorStateList, android.graphics.PorterDuff$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable
04-12 16:14:39.119 5796-5796/com.iekproject.siegfried.libraryapp D/AndroidRuntime: Shutting down VM
04-12 16:14:39.119 5796-5796/com.iekproject.siegfried.libraryapp E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.iekproject.siegfried.libraryapp, PID: 5796
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.iekproject.siegfried.libraryapp/com.iekproject.siegfried.libraryapp.MainActivity}: java.lang.IllegalStateException: This Activity already has an action bar supplied by the window decor. Do not request Window.FEATURE_SUPPORT_ACTION_BAR and set windowActionBar to false in your theme to use a Toolbar instead.
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2665)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
Caused by: java.lang.IllegalStateException: This Activity already has an action bar supplied by the window decor. Do not request Window.FEATURE_SUPPORT_ACTION_BAR and set windowActionBar to false in your theme to use a Toolbar instead.
at android.support.v7.app.AppCompatDelegateImplV9.setSupportActionBar(AppCompatDelegateImplV9.java:207)
at android.support.v7.app.AppCompatActivity.setSupportActionBar(AppCompatActivity.java:130)
at com.iekproject.siegfried.libraryapp.MainActivity.onCreate(MainActivity.java:30)
at android.app.Activity.performCreate(Activity.java:6679)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2618)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
any help is appreciated
You just need to set the content view after setting the toolbar. You can write like this :
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
setContentView(R.layout.activity_main);
The app is crashing because you are first setting the view and then setting the toolbar.
This question already has answers here:
This Activity already has an action bar supplied by the window decor
(25 answers)
Closed 6 years ago.
while I test my app, I get the follow error in the Android-Studio-Consol:
10-09 20:44:56.685 21573-21573/com.example.android.buyhatke E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.android.buyhatke, PID: 21573
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.android.buyhatke/com.example.android.buyhatke.HomeActivity}: java.lang.IllegalStateException: This Activity already has an action bar supplied by the window decor. Do not request Window.FEATURE_SUPPORT_ACTION_BAR and set windowActionBar to false in your theme to use a Toolbar instead.
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.IllegalStateException: This Activity already has an action bar supplied by the window decor. Do not request Window.FEATURE_SUPPORT_ACTION_BAR and set windowActionBar to false in your theme to use a Toolbar instead.
at android.support.v7.app.AppCompatDelegateImplV7.setSupportActionBar(AppCompatDelegateImplV7.java:198)
at android.support.v7.app.AppCompatActivity.setSupportActionBar(AppCompatActivity.java:130)
at com.example.android.buyhatke.HomeActivity.onCreate(HomeActivity.java:36)
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)
10-09 20:49:57.180 26089-26089/com.example.android.buyhatke W/System: ClassLoader referenced unknown path: /data/app/com.example.android.buyhatke-3/lib/x86
10-09 20:49:58.795 26089-26089/com.example.android.buyhatke W/System: ClassLoader referenced unknown path: /data/app/com.example.android.buyhatke-3/lib/x86
10-09 20:49:58.905 26089-26089/com.example.android.buyhatke W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter android.support.graphics.drawable.VectorDrawableCompat.updateTintFilter(android.graphics.PorterDuffColorFilter, android.content.res.ColorStateList, android.graphics.PorterDuff$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable
10-09 20:49:59.023 26089-26089/com.example.android.buyhatke D/AndroidRuntime: Shutting down VM
10-09 20:49:59.023 26089-26089/com.example.android.buyhatke E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.android.buyhatke, PID: 26089
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.android.buyhatke/com.example.android.buyhatke.HomeActivity}: java.lang.IllegalStateException: This Activity already has an action bar supplied by the window decor. Do not request Window.FEATURE_SUPPORT_ACTION_BAR and set windowActionBar to false in your theme to use a Toolbar instead.
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$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$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.IllegalStateException: This Activity already has an action bar supplied by the window decor. Do not request Window.FEATURE_SUPPORT_ACTION_BAR and set windowActionBar to false in your theme to use a Toolbar instead.
at android.support.v7.app.AppCompatDelegateImplV7.setSupportActionBar(AppCompatDelegateImplV7.java:198)
at android.support.v7.app.AppCompatActivity.setSupportActionBar(AppCompatActivity.java:130)
at com.example.android.buyhatke.HomeActivity.onCreate(HomeActivity.java:36)
at android.app.Activity.performCreate(Activity.java:6237)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$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)
My codes are
MainActivity.java
package com.example.android.buyhatke;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import com.facebook.CallbackManager;
import com.facebook.FacebookCallback;
import com.facebook.FacebookException;
import com.facebook.FacebookSdk;
import com.facebook.GraphRequest;
import com.facebook.GraphResponse;
import com.facebook.appevents.AppEventsLogger;
import com.facebook.login.LoginResult;
import com.facebook.login.widget.LoginButton;
import org.json.JSONObject;
public class MainActivity extends AppCompatActivity {
CallbackManager callbackManager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//
facebookSDKInitialize();
LoginButton loginButton = (LoginButton) findViewById(R.id.login_button);
loginButton.setReadPermissions("email");
getLoginDetails(loginButton);
}
/*
Initialize the facebook sdk.
And then callback manager will handle the login responses.<br />
*/
protected void facebookSDKInitialize() {
FacebookSdk.sdkInitialize(getApplicationContext());
callbackManager = CallbackManager.Factory.create();
}
/*
Register a callback function with LoginButton to respond to the login result.
On successful login,login result has new access token and recently granted permissions.
*/
protected void getLoginDetails(LoginButton login_button){
// Callback registration<br />
login_button.registerCallback(callbackManager, new FacebookCallback <LoginResult> (){
#Override
public void onSuccess(LoginResult login_result) {
getUserInfo(login_result);
}
#Override
public void onCancel() {
// code for cancellation
}
#Override
public void onError(FacebookException error) {
// code for error handling.
}
});
}
/*To get the facebook user's own profile information via creating a new request.
When the request is completed, a callback is called to handle the success condition. */
protected void getUserInfo(LoginResult login_result){
GraphRequest data_request = GraphRequest.newMeRequest(
login_result.getAccessToken(),
new GraphRequest.GraphJSONObjectCallback() {
#Override
public void onCompleted( JSONObject json_object, GraphResponse response) {
Intent intent = new Intent(MainActivity.this,HomeActivity.class);
intent.putExtra("jsondata",json_object.toString());
startActivity(intent);
}
});
Bundle permission_param = new Bundle();
permission_param.putString("fields", "id,name,email,picture.width(120).height(120)");
data_request.setParameters(permission_param);
data_request.executeAsync();
}
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
callbackManager.onActivityResult(requestCode, resultCode, data);
Log.e("data",data.toString());
}
#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.
return super.onOptionsItemSelected(item);
}
#Override
protected void onResume() {
super.onResume();
// Logs 'install' and 'app activate' App Events.
AppEventsLogger.activateApp(this);
}
#Override
protected void onPause() {
super.onPause();
// Logs 'app deactivate' App Event.
AppEventsLogger.deactivateApp(this);
}
}
HomeActivity.java
package com.example.android.buyhatke;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.NavigationView;
import android.support.design.widget.Snackbar;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import com.squareup.picasso.Picasso;
import org.json.JSONObject;
public class HomeActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {
JSONObject response, profile_pic_data, profile_pic_url;
TextView user_name, user_email;
ImageView user_picture;
NavigationView navigation_view;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
getSupportActionBar().setTitle("Home Page"); // may produce null pointer exception
Intent intent = getIntent();
String jsondata = intent.getStringExtra("jsondata");
setNavigationHeader(); // call setNavigationHeader Method.
setUserProfile(jsondata); // call setUserProfile Method
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
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 = (DrawerLayout) findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this,drawer,toolbar,R.string.openDrawer, R.string.closeDrawer);
try {
drawer.setDrawerListener(toggle);
}catch(NullPointerException e)
{
Context context = getApplicationContext();
CharSequence text = "Error";
int duration = Toast.LENGTH_SHORT;
Toast toast = Toast.makeText(context, text, duration);
toast.show();
}
toggle.syncState();
navigation_view.setNavigationItemSelectedListener(this);
}
#Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
}
/*
Set Navigation header by using Layout Inflater.<br />
*/
public void setNavigationHeader(){
navigation_view = (NavigationView) findViewById(R.id.nav_view);
View header = LayoutInflater.from(this).inflate(R.layout.nav_header_home, null);
navigation_view.addHeaderView(header);
user_name = (TextView) header.findViewById(R.id.username);
user_picture = (ImageView) header.findViewById(R.id.profile_pic);
user_email = (TextView) header.findViewById(R.id.email);
}
/*
Set User Profile Information in Navigation Bar.<br />
*/
public void setUserProfile(String jsondata){
try {
response = new JSONObject(jsondata);
user_email.setText(response.get("email").toString());
user_name.setText(response.get("name").toString());
profile_pic_data = new JSONObject(response.get("picture").toString());
profile_pic_url = new JSONObject(profile_pic_data.getString("data"));
Picasso.with(this).load(profile_pic_url.getString("url"))
.into(user_picture);
} catch (Exception e){
e.printStackTrace();
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.<br />
// getMenuInflater().inflate(R.menu.home, menu);<br />
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) {/** check if error*/
return true;
}
return super.onOptionsItemSelected(item);
}
#SuppressWarnings("StatementWithEmptyBody")
#Override
public boolean onNavigationItemSelected(MenuItem item){
// Handle navigation view item clicks here.
int id = item.getItemId();
if (id ==R.id.inbox) {
// Handle the camera action
} else if (id ==R.id.starred) {
}
else if (id ==R.id.sent_mail) {
}
else if (id ==R.id.drafts) {
}
else if (id ==R.id.allmail ) {
}
else if (id ==R.id.trash ) {
}
else if (id ==R.id.spam ) {
}
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
return true;
}
}
can anyone help?
In your styles.xml file, change your theme parent to NoActionBar if you are using Toolbar.
<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
I'm making an app that by now should save and then get the value of a numeric Edit Text. When i put to load data from string.xml it went fine, but when i switched to SharedPreferences it didn't even start. Any help finding the problem would be appreciated. BTW .java is below and i'm sure layout .xml is fine.
package programmingandroidapps.brightnesscustomizationapp;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Button;
import android.util.Log;
import android.content.SharedPreferences;
import android.content.Context;
public class MainActivity extends AppCompatActivity {
//Declarations
String brightnessValue;
int choice, brightnessValueInt;
final EditText mEditText1=(EditText)findViewById(R.id.editText1), mEditText2=(EditText)findViewById(R.id.editText2), mEditText3=(EditText)findViewById(R.id.editText3), mEditText4=(EditText)findViewById(R.id.editText4), mEditText5=(EditText)findViewById(R.id.editText5);
Button mButton1=(Button)findViewById(R.id.button1), mButton2=(Button)findViewById(R.id.button2), mButton3=(Button)findViewById(R.id.button3), mButton4=(Button)findViewById(R.id.button4), mButton5=(Button)findViewById(R.id.button5);
SharedPreferences storedBrightness1 = this.getSharedPreferences("brightv1", Context.MODE_PRIVATE), storedBrightness2 = this.getSharedPreferences("brightv2", Context.MODE_PRIVATE), storedBrightness3 = this.getSharedPreferences("brightv3", Context.MODE_PRIVATE), storedBrightness4 = this.getSharedPreferences("brightv4", Context.MODE_PRIVATE), storedBrightness5 = this.getSharedPreferences("brightv5", Context.MODE_PRIVATE);
SharedPreferences.Editor mEditor;
//
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Get saved brightness values from string.xml and set them to ediText1-5
brightnessValueInt = storedBrightness1.getInt("brightv1", 0);
brightnessIntToString();
printToEditText(1);
brightnessValueInt = storedBrightness2.getInt("brightv2", 0);
brightnessIntToString();
printToEditText(2);
brightnessValueInt = storedBrightness3.getInt("brightv3", 0);
brightnessIntToString();
printToEditText(3);
brightnessValueInt = storedBrightness4.getInt("brightv4", 0);
brightnessIntToString();
printToEditText(4);
brightnessValueInt = storedBrightness5.getInt("brightv5", 0);
brightnessIntToString();
printToEditText(5);
//
// On Click Button Listeners
mButton1.setOnClickListener(
new View.OnClickListener()
{
public void onClick(View view)
{
//Validate >=0 and <=100, paint #222222 if is valid, paint red if not
Log.v(brightnessValue, mEditText1.getText().toString());
mEditor = storedBrightness1.edit();
mEditor.putInt("brightv1", brightnessValueInt);
}
});
//
}
#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) {
return true;
}
return super.onOptionsItemSelected(item);
}
public void printToEditText(int choice)
{
if(choice==1)
{
mEditText1.setText(brightnessValue, TextView.BufferType.EDITABLE);
}
else if(choice==2)
{
mEditText2.setText(brightnessValue, TextView.BufferType.EDITABLE);
}
else if(choice==3)
{
mEditText3.setText(brightnessValue, TextView.BufferType.EDITABLE);
}
else if(choice==4)
{
mEditText4.setText(brightnessValue, TextView.BufferType.EDITABLE);
}
else
{
mEditText5.setText(brightnessValue, TextView.BufferType.EDITABLE);
}
}
public void brightnessIntToString()
{
brightnessValue=brightnessValueInt+"";
}
}
I believe this is the applications crash log. I'm new to Android so if it is not just say it, no need to get angry :P
05-01 13:24:53.061 1624-1624/programmingandroidapps.brightnesscustomizationapp D/dalvikvm: Not late-enabling CheckJNI (already on)
05-01 13:24:56.451 1624-1624/programmingandroidapps.brightnesscustomizationapp D/AndroidRuntime: Shutting down VM
05-01 13:24:56.451 1624-1624/programmingandroidapps.brightnesscustomizationapp W/dalvikvm: threadid=1: thread exiting with uncaught exception (group=0xb3d11b20)
05-01 13:24:56.471 1624-1624/programmingandroidapps.brightnesscustomizationapp E/AndroidRuntime:
FATAL EXCEPTION: main
Process: programmingandroidapps.brightnesscustomizationapp, PID: 1624
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{programmingandroidapps.brightnesscustomizationapp/programmingandroidapps.brightnesscustomizationapp.MainActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2110)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at android.app.Activity.findViewById(Activity.java:1884)
at programmingandroidapps.brightnesscustomizationapp.MainActivity.<init>(MainActivity.java:21)
at java.lang.Class.newInstanceImpl(Native Method)
at java.lang.Class.newInstance(Class.java:1208)
at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2101)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
The problem is that you are calling findViewById and getSharedPreferences before layout has been applied and the activity (this) was initialized. You should put those method calls in onCreate after setContentView(R.layout.activity_main);.
Dejan is right about moving part of the code into the onCreate lifecycle method, specifically, your code should change to something like this:
package programmingandroidapps.brightnesscustomizationapp;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Button;
import android.util.Log;
import android.content.SharedPreferences;
import android.content.Context;
public class MainActivity extends AppCompatActivity {
//Declarations
String brightnessValue;
int choice, brightnessValueInt;
private EditText mEditText1, mEditText2, mEditText3, mEditText4, mEditText5;
private Button mButton1,mButton2, mButton3, mButton4, mButton5;
private SharedPreferences storedBrightness1, storedBrightness2, storedBrightness3,storedBrightness4,storedBrightness5;
private SharedPreferences.Editor mEditor;
//
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mButton1 =(Button)findViewById(R.id.button1);
mButton2=(Button)findViewById(R.id.button2);
mButton3=(Button)findViewById(R.id.button3);
mButton4=(Button)findViewById(R.id.button4);
mButton5=(Button)findViewById(R.id.button5);
mEditText1 =(EditText)findViewById(R.id.editText1);
mEditText2=(EditText)findViewById(R.id.editText2);
mEditText3=(EditText)findViewById(R.id.editText3);
mEditText4=(EditText)findViewById(R.id.editText4);
mEditText5=(EditText)findViewById(R.id.editText5);
//instead of doing this, I'd rather use "named" SharedPreferences - call it "brightness" and will carry the five values
//something like SharedPreferences brightnessPreferences = this.getSharedPreferences("brightness", Context.MODE_PRIVATE);
//I ma just adding this here because that's the way you have it
storedBrightness1 = this.getSharedPreferences("brightv1", Context.MODE_PRIVATE),
storedBrightness2 = this.getSharedPreferences("brightv2", Context.MODE_PRIVATE),
storedBrightness3 = this.getSharedPreferences("brightv3", Context.MODE_PRIVATE),
storedBrightness4 = this.getSharedPreferences("brightv4", Context.MODE_PRIVATE),
storedBrightness5 = this.getSharedPreferences("brightv5", Context.MODE_PRIVATE);
//Get saved brightness values from string.xml and set them to ediText1-5
brightnessValueInt = storedBrightness1.getInt("brightv1", 0);
brightnessIntToString();
printToEditText(1);
brightnessValueInt = storedBrightness2.getInt("brightv2", 0);
brightnessIntToString();
printToEditText(2);
brightnessValueInt = storedBrightness3.getInt("brightv3", 0);
brightnessIntToString();
printToEditText(3);
brightnessValueInt = storedBrightness4.getInt("brightv4", 0);
brightnessIntToString();
printToEditText(4);
brightnessValueInt = storedBrightness5.getInt("brightv5", 0);
brightnessIntToString();
printToEditText(5);
//
// On Click Button Listeners
mButton1.setOnClickListener(
new View.OnClickListener()
{
public void onClick(View view)
{
//Validate >=0 and <=100, paint #222222 if is valid, paint red if not
Log.v(brightnessValue, mEditText1.getText().toString());
mEditor = storedBrightness1.edit();
mEditor.putInt("brightv1", brightnessValueInt);
}
});
//
}
#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) {
return true;
}
return super.onOptionsItemSelected(item);
}
public void printToEditText(int choice)
{
if(choice==1)
{
mEditText1.setText(brightnessValue, TextView.BufferType.EDITABLE);
}
else if(choice==2)
{
mEditText2.setText(brightnessValue, TextView.BufferType.EDITABLE);
}
else if(choice==3)
{
mEditText3.setText(brightnessValue, TextView.BufferType.EDITABLE);
}
else if(choice==4)
{
mEditText4.setText(brightnessValue, TextView.BufferType.EDITABLE);
}
else
{
mEditText5.setText(brightnessValue, TextView.BufferType.EDITABLE);
}
}
public void brightnessIntToString()
{
brightnessValue=brightnessValueInt+"";
}
}
I am a complete beginner to android/Java development and I massively appreciate any pointers anyone is able to give me on the issue I'm having. Here is the MainActivity.java.
package com.example.harris.enterappman;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
#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) {
return true;
}
return super.onOptionsItemSelected(item);
}
EditText enterName;
TextView usersName;
String str = enterName.getText().toString();
public void getName(View view){
enterName = (EditText) findViewById(R.id.enterName);
usersName = (TextView) findViewById(R.id.helloNameView);
usersName.setText(str);
}
public void printUsersName(){
}
}
Everytime I try and run the program, it fails with the error:
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.harris.enterappman/com.example.harris.enterappman.Main Activity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2121)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5021)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:827)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:643)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.example.harris.enterappman.MainActivity.<init>(MainActivity.java:48)
at java.lang.Class.newInstanceImpl(Native Method)
at java.lang.Class.newInstance(Class.java:1208)
at android.app.Instrumentation.newActivity(Instrumentation.java:1064)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2112)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5021)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:827)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:643)
at dalvik.system.NativeStart.main(Native Method)
From others posts online I have come to the conclusion that the problem is related to abstract methods? I was unable to work out how my code was wrong.
Cheers,
Harris
String str = enterName.getText().toString();
enterName is null at this point, as you are not setting it ever. You are welcome to declare String str; as a field, but you cannot initialize it until after you set a value on enterName.
You have code to initialize enterName in a somewhat strange getName() method, but you do not appear to be calling that ever.
you have not initialised entername properly
either use:
....
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
enterName = (EditText) findViewById(R.id.enterName);
usersName = (TextView) findViewById(R.id.helloNameView);
usersName.setText(str);
}
...
or use it like this:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
getName();
}
public void getName(){
enterName = (EditText) findViewById(R.id.enterName);
usersName = (TextView) findViewById(R.id.helloNameView);
usersName.setText(str);
}
You call enterName.getText() when enterName is null, which leads to NullPointerException.
Few things I suggest:
If you want to own references to the layout components, call these in the onCreate method:
enterName = (EditText) findViewById(R.id.enterName);
usersName = (TextView) findViewById(R.id.helloNameView);
Don't call methods in the class itself (except some constructors), call them in a method (I refer to the str variable).
how possible you are setting your str using enterName, as enterName is not initialized and hence it is null causing Null pointer exception
you must have to initilize enterName before using it, as you are doing initialization in your getName() method, and then use it to get its text
your code must be like this and you have to call this method from onCreate()
public void getName(View view){
enterName = (EditText) findViewById(R.id.enterName);
usersName = (TextView) findViewById(R.id.helloNameView);
usersName.setText(enterName.getText().toString());
}
Trying to set up the Navigation Drawer of an app right now, and every time I try to run the app on my Android device, I get a NullPointerException. The error is caused by getActionBar.setDisplayHomeUpAsEnabled(true) and getActionBar.setHomeButtonEnabled(true)
Even if I remove these two lines of code, I still get an error.
How do I fix this quickly?
Code:
import android.app.Activity;
import android.app.Fragment;
import android.content.res.Configuration;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.support.v7.app.ActionBarDrawerToggle;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.Window;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
public class MainActivity extends Activity {
private String[] navDrawerTitles;
private DrawerLayout navDrawerLayout;
private ListView mDrawerList;
private ActionBarDrawerToggle mDrawerToggle;
private CharSequence mTitle;
Fragment fragment = new Fragment();
private Fragment blankFrag = new Fragment();
private final int POSITION = 0;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
navDrawerTitles = getResources().getStringArray(R.array.nav_array);
navDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
mDrawerList = (ListView) findViewById(R.id.left_drawer);
// Set the adapter for the list view
mDrawerList.setAdapter(new ArrayAdapter<String>(this,
R.layout.drawer_list_item, navDrawerTitles));
mDrawerList.setOnItemClickListener(new DrawerItemClickListener());
getActionBar().setDisplayHomeAsUpEnabled(true);
getActionBar().setHomeButtonEnabled(true);
navDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
mDrawerToggle = new ActionBarDrawerToggle(this, /* host Activity */
navDrawerLayout, /* DrawerLayout object */
//R.drawable.ic_drawer, /* nav drawer icon to replace 'Up' caret */
R.string.drawer_open, /* "open drawer" description */
R.string.drawer_close /* "close drawer" description */
) {
/** Called when a drawer has settled in a completely closed state. */
public void onDrawerClosed(View view) {
// super.onDrawerClosed(view);
getActionBar().setTitle(R.string.app_name);
invalidateOptionsMenu();
}
/** Called when a drawer has settled in a completely open state. */
public void onDrawerOpened(View drawerView) {
// super.onDrawerOpened(drawerView);
getActionBar().setTitle(R.string.app_name);
invalidateOptionsMenu();
}
};
// Set the drawer toggle as the DrawerListener
navDrawerLayout.setDrawerListener(mDrawerToggle);
if (savedInstanceState == null) {
selectItem(0);
}
}
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu_main, 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 = navDrawerLayout.isDrawerOpen(mDrawerList);
menu.findItem(R.id.action_settings).setVisible(!drawerOpen);
return super.onPrepareOptionsMenu(menu);
}
public boolean onOptionsItemSelected(MenuItem item) {
// Pass the event to ActionBarDrawerToggle, if it returns
// true, then it has handled the app icon touch event
if (mDrawerToggle.onOptionsItemSelected(item)) {
return true;
}
return super.onOptionsItemSelected(item);
}
private class DrawerItemClickListener implements
ListView.OnItemClickListener {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {
selectItem(position);
}
}
/** Swaps fragments in the main content view */
/**
* Starts an Activity when item is clicked
*/
private void selectItem(int position) {
// }
Bundle args = new Bundle();
args.putInt(StartingFragment.TEA_TYPE_POS, position);
fragment.setArguments(args);
// Highlight the selected item, update the title, and close the drawer
mDrawerList.setItemChecked(position, true);
// setTitle(navDrawerTitles[position]);
navDrawerLayout.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);
mDrawerToggle.onConfigurationChanged(newConfig);
}
}
01-31 14:11:11.298: E/AndroidRuntime(20904): FATAL EXCEPTION: main
01-31 14:11:11.298: E/AndroidRuntime(20904): Process:
appathon.bu.com.appathon, PID: 20904 01-31 14:11:11.298:
E/AndroidRuntime(20904): java.lang.RuntimeException: Unable to start
activity
ComponentInfo{appathon.bu.com.appathon/appathon.bu.com.appathon.MainActivity}:
java.lang.NullPointerException 01-31 14:11:11.298:
E/AndroidRuntime(20904): at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2212)
01-31 14:11:11.298: E/AndroidRuntime(20904): at
android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2271)
01-31 14:11:11.298: E/AndroidRuntime(20904): at
android.app.ActivityThread.access$800(ActivityThread.java:144) 01-31
14:11:11.298: E/AndroidRuntime(20904): at
android.app.ActivityThread$H.handleMessage(ActivityThread.java:1205)
01-31 14:11:11.298: E/AndroidRuntime(20904): at
android.os.Handler.dispatchMessage(Handler.java:102) 01-31
14:11:11.298: E/AndroidRuntime(20904): at
android.os.Looper.loop(Looper.java:136) 01-31 14:11:11.298:
E/AndroidRuntime(20904): at
android.app.ActivityThread.main(ActivityThread.java:5146) 01-31
14:11:11.298: E/AndroidRuntime(20904): at
java.lang.reflect.Method.invokeNative(Native Method) 01-31
14:11:11.298: E/AndroidRuntime(20904): at
java.lang.reflect.Method.invoke(Method.java:515) 01-31 14:11:11.298:
E/AndroidRuntime(20904): at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:796)
01-31 14:11:11.298: E/AndroidRuntime(20904): at
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:612) 01-31
14:11:11.298: E/AndroidRuntime(20904): at
dalvik.system.NativeStart.main(Native Method) 01-31 14:11:11.298:
E/AndroidRuntime(20904): Caused by: java.lang.NullPointerException
01-31 14:11:11.298: E/AndroidRuntime(20904): at
appathon.bu.com.appathon.MainActivity.onCreate(MainActivity.java:45)
01-31 14:11:11.298: E/AndroidRuntime(20904): at
android.app.Activity.performCreate(Activity.java:5231) 01-31
14:11:11.298: E/AndroidRuntime(20904): at
android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
01-31 14:11:11.298: E/AndroidRuntime(20904): at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2169)
01-31 14:11:11.298: E/AndroidRuntime(20904): ... 11 more
First, if getActionBar() in an Activity is returning null, then you do not have a native action bar in your activity.
Second, android.support.v7.app.ActionBarDrawerToggle does not work with the native action bar. It works with the appcompat-v7 action bar backport. If you are going to use android.support.v7.app.ActionBarDrawerToggle, then you have to move your app over to use appcompat-v7:
Add appcompat-v7 as a dependency
Inherit from ActionBarActivity instead of Activity
Call getSupportActionBar() rather than getActionBar()
Use Theme.AppCompat (or something that inherits from it) as your activity's theme
I had the same error as you. My solution was to set theme with ThemeAppCompat, make your activity extend AppCompatActivity and use the method of getSupportActionBar instead of using the method of getActionBar. In short, you should make sure the actionBar of theme and the method which to get actionBar have the same support library.