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google tells me that my app crashes on (only) Google Pixel 2 (virtuel)

I'm trying to publish my app in google play console.
But it tells me that it crashes on Google Pixel 2 (virtuel) (works on the 9 others) with 2 errors (very similar)
Google Pixel 2 (virtuel) 1080x1920 Android 12 (SDK 31) - x86_64 en_US
Error:
java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.activity.result.ActivityResultLauncher.launch(java.lang.Object)' on a null object reference
Detail:
FATAL EXCEPTION: Thread-2
Process: xxxxxxxx, PID: 8724
java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.activity.result.ActivityResultLauncher.launch(java.lang.Object)' on a null object reference
at xxxxxxxx.models.StockInputDialog.lambda$init$9$xxxxxxxx-models-StockInputDialog(StockInputDialog.java:417)
at xxxxxxxx.models.StockInputDialog$$ExternalSyntheticLambda9.onClick(Unknown Source:2)
at android.view.View.performClick(View.java:7441)
at android.view.View.performClickInternal(View.java:7418)
at android.view.View.access$3700(View.java:835)
at android.view.View$PerformClick.run(View.java:28676)
at android.os.Handler.handleCallback(Handler.java:938)
at android.os.Handler.dispatchMessage(Handler.java:99)
at androidx.test.espresso.base.Interrogator.loopAndInterrogate(Interrogator.java:10)
at androidx.test.espresso.base.UiControllerImpl.loopUntil(UiControllerImpl.java:7)
at androidx.test.espresso.base.UiControllerImpl.loopUntil(UiControllerImpl.java:1)
at androidx.test.espresso.base.UiControllerImpl.injectMotionEvent(UiControllerImpl.java:5)
at androidx.test.espresso.action.MotionEvents.sendUp(MotionEvents.java:6)
at androidx.test.espresso.action.MotionEvents.sendUp(MotionEvents.java:1)
at androidx.test.espresso.action.Tap.sendSingleTap(Tap.java:5)
at androidx.test.espresso.action.Tap.-$$Nest$smsendSingleTap(Unknown Source:0)
at androidx.test.espresso.action.Tap$1.sendTap(Tap.java:1)
at androidx.test.espresso.action.GeneralClickAction.perform(GeneralClickAction.java:4)
at androidx.test.espresso.ViewInteraction$SingleExecutionViewAction.perform(ViewInteraction.java:2)
at androidx.test.espresso.ViewInteraction.doPerform(ViewInteraction.java:21)
at androidx.test.espresso.ViewInteraction.-$$Nest$mdoPerform(Unknown Source:0)
at androidx.test.espresso.ViewInteraction$1.call(ViewInteraction.java:6)
at androidx.test.espresso.ViewInteraction$1.call(ViewInteraction.java:1)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at android.os.Handler.handleCallback(Handler.java:938)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loopOnce(Looper.java:201)
at android.os.Looper.loop(Looper.java:288)
at android.app.ActivityThread.main(ActivityThread.java:7839)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1003)
My code is explained (and the reason why) startActivityForResult migration, call registerForActivityResult outside activity, and simplified to the maximum:
public class StockActivity extends AppCompatActivity implements DialogCloseListener {
private ActivityResultLauncher<Intent> stockGalleryActivityResultLauncher;
private ActivityResultLauncher<Intent> stockCameraActivityResultLauncher;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
stockCameraActivityResultLauncher = registerForActivityResult(new ActivityResultContracts.StartActivityForResult(),
result -> {
// code
});
stockGalleryActivityResultLauncher = registerForActivityResult(new ActivityResultContracts.StartActivityForResult(),
result -> {
// code
});
}
#Override
public boolean onOptionsItemSelected(#NonNull MenuItem item) {
if (id == R.id.action_add) {
mStockInputDialog = new StockInputDialog(this, stockCameraActivityResultLauncher, stockGalleryActivityResultLauncher,);
return true;
} else {
return super.onOptionsItemSelected(item);
}
}
}
public class StockInputDialog {
private final Context mContext;
private AlertDialog mInputDialog;
private ActivityResultLauncher<Intent> stockCameraActivityResultLauncher;
private ActivityResultLauncher<Intent> stockGalleryActivityResultLauncher;
public StockInputDialog(Context context, ActivityResultLauncher<Intent> pStockCameraActivityResultLaunchera, ActivityResultLauncher<Intent> pStockGalleryActivityResultLauncher) {
mContext = context;
stockCameraActivityResultLauncher = pStockCameraActivityResultLaunchera;
stockGalleryActivityResultLauncher = pStockGalleryActivityResultLauncher;
LayoutInflater li = LayoutInflater.from(this.mContext);
mPromptsView = li.inflate(R.layout.text_input_stock, null);
final AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(this.mContext);
alertDialogBuilder.setView(mPromptsView);
final ImageButton imgButtonCam = mPromptsView.findViewById(R.id.addCam);
final ImageButton imgButtonGal = mPromptsView.findViewById(R.id.addGal);
imgButtonCam.setOnClickListener(view -> {
Uri uri = FileProvider.getUriForFile(mContext, "fr.foo.bar.provider",
new Product(Consts.TEMP_NUM).getIMGPathCacheFile(mContext));
Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
intent.putExtra(MediaStore.EXTRA_OUTPUT, uri);
stockCameraActivityResultLauncher.launch(intent); <= ERROR
});
imgButtonGal.setOnClickListener(view -> {
stockGalleryActivityResultLauncher.launch(new Intent(Intent.ACTION_PICK, MediaStore.Images.Media.EXTERNAL_CONTENT_URI)) <= ERROR
});
}
}
The 2 errors correspond to the 2 launch()
What I don't understand is that I'm using this same principle elsewhere in the application without an error being raised.

No more crashes when testing the "nullity" of the launchers (#Abdo21 2nd answer).
imgButtonCam.setOnClickListener(view -> {
Uri uri = FileProvider.getUriForFile(mContext, "fr.novazur.donteat.provider",
new Product(Consts.TEMP_NUM).getIMGPathCacheFile(mContext));
if (stockCameraActivityResultLauncher != null)
stockCameraActivityResultLauncher.launch(uri);
else
Toast.makeText(mContext, R.string.featureAbsent, Toast.LENGTH_LONG).show();
});
imgButtonGal.setOnClickListener(view -> {
if (stockGalleryActivityResultLauncher != null)
stockGalleryActivityResultLauncher.launch("image/*");
else
Toast.makeText(mContext, R.string.featureAbsent, Toast.LENGTH_LONG).show();
});
That's what I should have done from the start. I'm a little sorry for not having thought of it, it's so obvious. I guess it's related to the creation of the AlertDialog which should not allow immediate access to the launchers. What I don't understand in this case is why only the Pixel 2 crashes, but problem seems to be solved for the moment. Thanks all.

FirebaseRecyclerAdapter throws a null object [duplicate]

This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 3 years ago.
My app crashes right away after signin and it gives a null object on
adapter = new FirebaseRecyclerAdapter<Category, MenuViewHolder>(Category.class, R.layout.menu_item, MenuViewHolder.class, category)
Can someone help or have any better idea?
private void LoadMenu(){
adapter = new FirebaseRecyclerAdapter<Category, MenuViewHolder>(Category.class, R.layout.menu_item, MenuViewHolder.class, category) {
#Override
protected void populateViewHolder(MenuViewHolder viewHolder, Category model, int position) {
viewHolder.txtMenuName.setText(model.getName());
Picasso.get().load(model.getImage()).into(viewHolder.imageView);
final Category clickItem = model;
viewHolder.setItemClickListener(new ItemClickListener() {
#Override
public void onClick(View v, int position, boolean isLongClick) {
//Get CategoryId and send to new Activity
Intent foodList = new Intent(Home.this, FoodList.class);
//Because Category is key, so we just get the key of this item
foodList.putExtra("CategoryId", adapter.getRef(position).getKey());
startActivity(foodList);
}
});
}
};
recycler_menu.setAdapter(adapter);
}
this is the full stacktrace error that crashes my app, I dont know why, Iv'e initiated the FireDatabase and set the database reference to "Category" which is in my firedatabase
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.fahad.foodie, PID: 4287
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
at com.fahad.foodie.Home$2.populateViewHolder(Home.java:88)
at com.fahad.foodie.Home$2.populateViewHolder(Home.java:85)
at com.firebase.ui.database.FirebaseRecyclerAdapter.onBindViewHolder(FirebaseRecyclerAdapter.java:184)
at android.support.v7.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:6781)
at android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:6823)
at android.support.v7.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:5752)
at android.support.v7.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:6019)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5858)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5854)
at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2230)
at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1557)
at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1517)
at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:612)
at android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3924)
at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:3641)
at android.support.v7.widget.RecyclerView.consumePendingUpdateOperations(RecyclerView.java:1888)
at android.support.v7.widget.RecyclerView$1.run(RecyclerView.java:407)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:949)
at android.view.Choreographer.doCallbacks(Choreographer.java:761)
at android.view.Choreographer.doFrame(Choreographer.java:693)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:935)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:214)
at android.app.ActivityThread.main(ActivityThread.java:6981)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1445)

Your textview is not properly defined.
viewHolder.txtMenuName is NULL as per the logcat messages.
Please define it properly at your MenuViewHolder like below,
public MenuViewHolder(View itemView) {
super(itemView);
txtMenuName = itemView.findViewById(R.id.menu_name);
imageMenu = itemView.findViewById(R.id.menu_image);
itemView.setOnClickListener(this);
}
You have to ensure the txtMenuName is properly mapped to the textview id(for example android:id="#+id/menu_name") in the menu_item.xml.

Why does my Activity get destroyed upon adding a fragment (#2)?

I want to make it clear that this question will look very similar to one I asked earlier, but that I'm not asking exactly the same thing.
In my previous question, I got a RuntimeException/IllegalStateException, which told me my Activity got destroyed upon adding a new fragment.
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.tim.timapp
/com.example.tim.timapp.MainActivity}: java.lang.IllegalStateException:
Activity has been destroyed
In that case, it turned out it had to do with me creating new instances of MainActivityin an invalid way:
MainActivity ma = new MainActivity();
(PSA: Don't do the above, use MainActivity ma = (MainActivity) getActivity(); instead.)
I have now corrected this in my entire project, and am getting almost exactly the same error. Let me be clear: I (think I) know the original error was fixed, because I got a different error in between these two RE's, which I was able to fix myself.
To reiterate on my gibberish: Got the first RE, fixed it with the answer on my question, got a different error, fixed that myself, got almost exactly the same RE.
I have searched through my entire project to see if I had anything similar to the error I made before, but I can't find anything, so here I am. So basically, the answer I got on my previous question fixed my issue, temporarily. That answer however, does not help me with this new error I'm getting, that's why I'm asking this question.
TL;DR: Answer on Q1 fixed my issue at first(which makes it a working answer), but it does not fix the issue I'm having right now, which is almost the same.
The actual question
So, now we've got that bit out of the way, let's get on with my issue. So, I'm getting a RuntimeException/IllegalStateExcetion:
java.lang.RuntimeException: Unable to start activity
ComponentInfo{com.example.tim.timapp/com.example.tim.timapp.MainActivity}:
java.lang.IllegalStateException: Activity has been destroyed
(PS. It's only a RE because I have my app navigate to the GeneralSettings fragment on startup, for debugging ease.)
I've read up on this kind of error, but nothing I could find that applies on my project.
So, what is causing this RuntimeException/IllegalStateException?
Full log
04-05 14:17:53.140 23411-23411/? I/art: Not late-enabling -Xcheck:jni (already on)
04-05 14:17:53.190 23411-23411/com.example.tim.timapp W/System: ClassLoader referenced unknown path: /data/app/com.example.tim.timapp-1/lib/x86_64
04-05 14:17:53.210 23411-23411/com.example.tim.timapp D/TEST DBHandler: sInstance == null
04-05 14:17:53.370 23411-23411/com.example.tim.timapp D/AndroidRuntime: Shutting down VM
04-05 14:17:53.370 23411-23411/com.example.tim.timapp E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.tim.timapp, PID: 23411
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.tim.timapp/com.example.tim.timapp.MainActivity}: java.lang.IllegalStateException: Activity has been destroyed
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: Activity has been destroyed
at android.app.FragmentManagerImpl.enqueueAction(FragmentManager.java:1433)
at android.app.BackStackRecord.commitInternal(BackStackRecord.java:687)
at android.app.BackStackRecord.commit(BackStackRecord.java:663)
at com.example.tim.timapp.MainActivity.DrawVariableFragments(MainActivity.java:276)
at com.example.fragments.Settings.GeneralSettingsFragment.onCreateView(GeneralSettingsFragment.java:58)
at android.app.Fragment.performCreateView(Fragment.java:2220)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:973)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1148)
at android.app.BackStackRecord.run(BackStackRecord.java:793)
at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1535)
at android.app.FragmentController.execPendingActions(FragmentController.java:325)
at android.app.Activity.performStart(Activity.java:6252)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2379)
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) 
MainActivity (Snippet)
package com.example.tim.timapp;
public class MainActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
private static boolean isMainShown = false;
private static boolean isSettingsShown = false;
private static boolean doSavePopup = false;
private static String backTitle = "";
private String tag = "TEST MA";
DBHandler dbHandler;
Menu menu;
public void DrawVariableFragments(String base,String token){
// FragmentManager fm = getFragmentManager();
ArrayList<String> Data;
dbHandler = DBHandler.getInstance(this);
int AmountOfEntries;
int SettingsContainer;
String SettingsTag;
Fragment SettingsVariableFragment;
Fragment SettingsEmptyFragment;
if (base.equalsIgnoreCase("StuffManager")) {
Data = new ArrayList<String>() {{add("StuffManager"); add("name"); add("tag"); }};
SettingsContainer = R.id.FragmentContainer2;
SettingsTag = getString(R.string.navdrawer_stuffmanager);
SettingsVariableFragment = new StuffManagerVariableFragment();
SettingsEmptyFragment = new StuffManagerEmptyFragment();
} else if (base.equalsIgnoreCase("GeneralSettings")) {
Data = new ArrayList<String>() {{add("GeneralSettings"); add("name"); add("ip"); add("port"); add("username"); add("pass"); }};
SettingsContainer = R.id.FragmentContainerGeneralSettings;
SettingsTag = getString(R.string.navdrawer_generalsettings);
SettingsVariableFragment = new GeneralSettingsVariableFragment();
SettingsEmptyFragment = new GeneralSettingsEmptyFragment();
} else {
Log.e(tag, "String Base not recognised");
return;
}
AmountOfEntries = dbHandler.returnArray(base, Data.get(1)).size();
FragmentManager fm = getFragmentManager().findFragmentByTag(SettingsTag).getChildFragmentManager();
if ((dbHandler.returnArray(base, Data.get(1))).size() == 0 ) {
// Log.d(tag, "SettingsContainer1: " + String.valueOf(SettingsContainer) + "; SettingsEmtpyFragment1: " + SettingsEmptyFragment + "; Base1: " + base);
fm.beginTransaction().add(SettingsContainer, SettingsEmptyFragment, (base + "EmptyFragment")).commit();
fm.executePendingTransactions();
return;
}
if (AmountOfEntries > 0) {
String EmptyFragName = (base + "EmptyFragment");
if ((fm.findFragmentByTag(EmptyFragName)) != null) {
fm.beginTransaction().remove(fm.findFragmentByTag(EmptyFragName)).commit();
fm.executePendingTransactions();
}
for (int i = 0; i < AmountOfEntries; i++) {
ArrayList<String> fragmentData = new ArrayList<>();
for (int k=1; k < Data.size(); k++) {
int j=k-1;
fragmentData.set(j, (dbHandler.returnArray(base, Data.get(k)).get(j)));
}
if (token.equalsIgnoreCase("edit")) {
LinearLayout linearLayout = (LinearLayout) findViewById(SettingsContainer);
linearLayout.removeAllViews();
DrawVariableFragments(base ,"draw");
} else if (token.equalsIgnoreCase("add")) {
if (fm.findFragmentByTag(fragmentData.get(i)) == null) {
fm.beginTransaction().add(SettingsContainer, SettingsVariableFragment, fragmentData.get(0)).commit();
fm.executePendingTransactions();
if (base.equalsIgnoreCase("StuffManager")) {
((StuffManagerVariableFragment) fm
.findFragmentByTag(fragmentData.get(i)))
.setText(fragmentData.get(0), fragmentData.get(1));
} else if (base.equalsIgnoreCase("GeneralSettings")) {
((GeneralSettingsVariableFragment) fm
.findFragmentByTag(fragmentData.get(i)))
.setText(fragmentData.get(0), fragmentData.get(1), fragmentData.get(2), fragmentData.get(3));
}
}
} else if (token.equalsIgnoreCase("draw")) {
fm.beginTransaction().add(SettingsContainer, SettingsVariableFragment, fragmentData.get(0)).commit();
fm.executePendingTransactions();
if (base.equalsIgnoreCase("StuffManager")) {
((StuffManagerVariableFragment) fm
.findFragmentByTag(fragmentData.get(i)))
.setText(fragmentData.get(0), fragmentData.get(1));
} else if (base.equalsIgnoreCase("GeneralSettings")) {
((GeneralSettingsVariableFragment) fm
.findFragmentByTag(fragmentData.get(i)))
.setText(fragmentData.get(0), fragmentData.get(1), fragmentData.get(2), fragmentData.get(3));
}
}
}
} else {
Log.d("TEST", "WTF, nameArray.size != 0 && !> 0");
}
}
}
GeneralSettingsFragment (Snippet)
package com.example.fragments.Settings;
public class GeneralSettingsFragment extends Fragment {
MainActivity ma;
DBHandler dbHandler;
private static Menu optionsMenu;
public static boolean hideDeleteAllButton = false;
LinearLayout linearLayout;
View rootView;
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.fragment_generalsettings, container, false);
ma = (MainActivity) getActivity();
linearLayout = (LinearLayout) rootView.findViewById(R.id.FragmentContainerGeneralSettings);
if (linearLayout == null) {
Log.e("GMF", "Layout is null");
} else if (linearLayout.getChildCount() == 0) {
GeneralSettingsInitialInputDialog GSIID = new GeneralSettingsInitialInputDialog();
GSIID.show(getFragmentManager(), "dialog");
hideDeleteAllButton = true;
} else {
hideDeleteAllButton = false;
}
ma.DrawVariableFragments("GeneralSettings", "draw");
return rootView;
}
}

You are still doing things in an unsupported way. In MainActivity.DrawVariableFragments() you are creating a new GeneralSettingsVariableFragment() and then call getChildFragmentManager() on it and attempt to commit a fragment.
The GeneralSettingsFragment has not yet been attached to an Activity so it does not have a host. This throws the IllegalStateException("Activity has been destroyed") exception you are seeing when you try to commit the FragmentTransaction.
It is unclear why you are creating a new GeneralSettingsVariableFragmentwhen you are already inside a new instance of one.
To properly lookup an existing fragment use getFragmentManager().findFragmentByTag(...) or getFragmentManager().findFragmentById(...).

Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference

The problem is as follows. I have a login activity (in Android Studio) which worked fine a few days before. I don't remember changing anything but when I run this one the previous time the app closed right after I clicked the login button. The last thing indicated was the toast about pre-execution of AsyncTask.
And I can't understand why there could be a NullPointerException.
I have almost the same code for my signup activity and it works fine.
Here is the log:
05-28 16:04:52.395 1218-1232/system_process V/WindowManager﹕ addAppToken: AppWindowToken{5d89eb token=Token{23ccc93a ActivityRecord{2fe54865 u0 utanashati.reminder/.HomepageActivity t17}}} to stack=1 task=17 at 1
05-28 16:04:52.407 19927-19927/utanashati.reminder D/AndroidRuntime﹕ Shutting down VM
05-28 16:04:52.408 19927-19927/utanashati.reminder E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: utanashati.reminder, PID: 19927
java.lang.RuntimeException: Unable to start activity
ComponentInfo{utanashati.reminder/utanashati.reminder.HomepageActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2325)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2390)
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:5257)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
at utanashati.reminder.HomepageActivity.onCreate(HomepageActivity.java:55)
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:2390)
            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:5257)
            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)
05-28 16:04:52.410 1218-1232/system_process W/ActivityManager﹕ Force finishing activity 1 utanashati.reminder/.HomepageActivity
05-28 16:04:52.411 1218-1232/system_process W/ActivityManager﹕ Force finishing activity 2 utanashati.reminder/.LoginActivity
EDIT 1
I had my eyes opened, the problem is not with LoginActivity, but with HomepageActivity. Here is the code:
import ...
public class HomepageActivity extends Activity implements AdapterView.OnItemSelectedListener {
protected EditText mAddTaskText;
protected Spinner mPrioritySpinner;
protected Button mAddTaskButton;
protected int intPriority = 0;
protected String taskText;
protected Timestamp taskTimestamp;
protected Task userTask;
protected JsonGenerator taskJSON;
#Override
protected void onCreate(Bundle savedInstanceState) { // Starts activity. The state can be restored from savedInstanceState
super.onCreate(savedInstanceState); // Calls the superclass method (IMPORTANT)
setContentView(R.layout.activity_homepage); // Sets layout from activity_homepage.xml
mPrioritySpinner = (Spinner) findViewById(R.id.prioritySpinner); // Creates an ArrayAdapter using the string array and a default spinner layout
ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,
R.array.priorityList, android.R.layout.simple_spinner_item); // Specifies the layout to use when the list of choices appears
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); // Applies the adapter to the spinner
mPrioritySpinner.setAdapter(adapter);
mPrioritySpinner.setOnItemSelectedListener(this);
mAddTaskText = (EditText) findViewById(R.id.addTaskEditText); // Finds View by its id in .xml file
mAddTaskButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Toast.makeText(HomepageActivity.this, "Done!", Toast.LENGTH_LONG).show();
Calendar taskCalendar = Calendar.getInstance(); // Creates new calendar
long taskTime = taskCalendar.getTimeInMillis(); // Gets time in milliseconds
taskTimestamp = new Timestamp(taskTime); // Creates new Timestamp
taskText = mAddTaskText.getText().toString(); // Gets description of the task
userTask.setDate(taskTimestamp); // Sets date
userTask.setText(taskText); // Sets text
/* Creating JsonGenerator */
ObjectMapper mapper = new ObjectMapper();
try {
mapper.writeValue(taskJSON, userTask);
}
catch (IOException e) {
Toast.makeText(HomepageActivity.this, "Could not create JSON", Toast.LENGTH_LONG).show();
}
/* Getting out email and password */
String userPassword = ((EmailPassword) HomepageActivity.this.getApplication()).getPassword();
String userEmail = ((EmailPassword) HomepageActivity.this.getApplication()).getUserEmail();
Toast.makeText(HomepageActivity.this, userEmail + " " + userPassword, Toast.LENGTH_LONG).show();
/* HTTP stuff */
HttpPoster get = new HttpPoster();
get.execute(userEmail, userPassword, taskJSON.toString());
}
});
}
public int getData (String username, String password, String taskJSON) {
try {
HttpPost httpPost = new HttpPost("http://something.com/" + username + "/tasks");
String dataToEncode = username + ":" + password;
String encodedData = Base64.encodeToString(dataToEncode.getBytes(), Base64.NO_WRAP);
httpPost.setHeader("Authorization", encodedData);
try {
StringEntity taskEntity = new StringEntity(taskJSON, "UTF-8");
httpPost.setEntity(taskEntity);
}
catch (UnsupportedEncodingException e) {
Toast.makeText(HomepageActivity.this, "Unsupported encoding", Toast.LENGTH_LONG).show();
}
HttpClient client = new DefaultHttpClient();
HttpResponse response = client.execute(httpPost);
StatusLine statusLine = response.getStatusLine();
int statusCode = statusLine.getStatusCode();
if (statusCode == 200) {
return 1;
}
else if (statusCode == 404) { return 2; }
else if (statusCode == 500) { return 3; }
else if (statusCode == 409) { return 4; }
else { return statusCode; }
}
catch (IOException e) {
e.printStackTrace();
}
return 0;
}
public void onItemSelected(AdapterView<?> parent, View view,
int pos, long id) {
String priority = parent.getItemAtPosition(pos).toString(); // Gets chosen priority
Toast.makeText(HomepageActivity.this, priority, Toast.LENGTH_LONG).show();
while (!((priority.equals("Low")) || (priority.equals("Medium")) || (priority.equals("High")))) {
Toast.makeText(HomepageActivity.this, "Something bad happened. Try to choose again", Toast.LENGTH_LONG).show();
}
if (priority.equals("Low")) {
intPriority = 0;
}
else if (priority.equals("Medium")) {
intPriority = 1;
}
else if (priority.equals("High")) {
intPriority = 2;
}
userTask.setPriority(intPriority); // Sets chosen priority
}
public void onNothingSelected(AdapterView<?> parent) {
userTask.setPriority(intPriority); // Sets default priority ("0")
}
public class HttpPoster extends AsyncTask<String, Void, Integer> {
#Override
protected void onPreExecute() {
super.onPreExecute();
}
#Override
protected Integer doInBackground(String... params) {
return getData(params[0], params[1], params[3]);
}
#Override
protected void onPostExecute(Integer result) {
super.onPostExecute(result);
if (result == 1) {
Toast.makeText(HomepageActivity.this, "Login successful", Toast.LENGTH_LONG).show();
Intent takeUserHome = new Intent(HomepageActivity.this, HomepageActivity.class);
startActivity(takeUserHome);
}
else if (result == 2) {
Toast.makeText(HomepageActivity.this, "No such user", Toast.LENGTH_LONG).show();
}
else if (result == 3) {
Toast.makeText(HomepageActivity.this, "Internal server error: unable to send email", Toast.LENGTH_LONG).show();
}
else if (result == 4) {
Toast.makeText(HomepageActivity.this, "Task already exists", Toast.LENGTH_LONG).show();
}
else {
Toast.makeText(HomepageActivity.this, result.toString(), Toast.LENGTH_LONG).show();
}
}
}
}
And XML file:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
android:paddingBottom="#dimen/activity_vertical_margin"
tools:context="utanashati.testapp.HomepageActivity">
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="Add a new task..."
android:id="#+id/addTaskEditText"
android:nestedScrollingEnabled="false"
android:minLines="1"
android:maxLines="1" />
<Spinner
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="#+id/prioritySpinner"
android:layout_alignRight="#+id/addTaskButton"
android:layout_alignEnd="#+id/addTaskButton"
android:layout_below="#+id/addTaskEditText" />
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Add task"
android:id="#+id/addTaskButton"
android:layout_below="#+id/prioritySpinner"
android:layout_centerHorizontal="true" />
</RelativeLayout>

It seems the button you are invoking is not in the layout you are using in setContentView(R.layout.your_layout)
Check it.

mAddTaskButton is null because you never initialize it with:
mAddTaskButton = (Button) findViewById(R.id.addTaskButton);
before you call mAddTaskButton.setOnClickListener().

Check out this solution. It worked for me.....
Check the id of the button for which the error is raised...it may be the same in any one of the other page in your app.
If yes, then change the id of them and then the app runs perfectly.
I was having two same button id's in two different XML codes....I changed the id. Now it runs perfectly!!
Hope it works

That true,Mustafa....its working..its point to two layout
setContentView(R.layout.your_layout)
v23(your_layout).
You should take Button both activity layout...
solve this problem successfully

Check whether you have matching IDs in both Java and XML

Just define the button as lateinit var at top of your class:
lateinit var buttonOk: Button
When you want to use a button in another layout you should define it in that layout. For example if you want to use button in layout which name is 'dialogview', you should write:
buttonOk = dialogView.findViewById<Button>(R.id.buttonOk)
After this you can use setonclicklistener for the button and you won't have any error.
You can see correct answer of this question: Android Kotlin findViewById must not be null

Make sure that while using :
Button "varName" =findViewById("btID");
you put in the right "btID". I accidentally put in the id of a button from another similar activity and it showed the same error. Hope it helps.

Got the same error,
CHECK THIS : MINOR SILLY MISTAKE
check findviewbyid(R.id.yourID);
If you have put the id correct or not.

i had the same problem and it seems like i didn't initiate the button used with click listener, in other words id didn't te

Placing setOnClickListener in onStart method solved the problem for me.
Checkout "Android Lifecycle concept" for further clarification

mAddTaskButton.setOnClickListener(new View.OnClickListener()
you have a click listner but you haven't initialized the mAddTaskButton with your layout binding

Please check whether you have two Layout folder (e.g Layout & Layout-V21). The XML file should be same in both folders. That was the case for me.

saving multiple values from one changing TextView using shared preferences?

I have one textView value that the can be changed using a plus and minus button. (like androids number picker object but custom.)
I need to be able to extract each value and save if depending on a spinner value that is set by the user.
For each value that is saved for each spinner position, when the user returns to the same position on the spinner, the previous value entered will appear indicating a value has already been entered.
For Instance:(If spinner is the day of the week)(value is the TextView/custom Spinner) "If the user selects Wednesday, and picks a value of 7, then goes to Monday and picks 8, if the user returns to Wednesday the value entered before (7) will show, if the user returns to Monday the value 8 will show.
Spinner code
final Spinner spinner1 = (Spinner) findViewById(R.id.sp_dotw);
final ArrayAdapter<CharSequence> adapter =
ArrayAdapter.createFromResource(this, R.array.dotw_array, R.layout.custom_spinner);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner1.setAdapter(adapter);
spinner1.setOnItemSelectedListener(new OnItemSelectedListener() {
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
spinner1position = position;
spinnerPos();
showToast("spinnerdotw: position= " + position + "id=" + id);
}
public void onNothingSelected(AdapterView<?> adapterView) {
showToast("No Dotw selected");
}
});
Number picker code
#Override
public void onClick(View v) {
String getString = String.valueOf(tvSony.getText());
int current1 = Integer.parseInt(getString);
if (v == btnUp1) {
if (current1 < nEnd) {
current1++;
tvSony.setText(String.valueOf(current1));
}
}
if (v == btnDown1) {
if (current1 > nStart) {
current1--;
tvSony.setText(String.valueOf(current1));
}
}
sonyRs = current1;
}
Any Suggestions on how to do this would be highly appreciated ?
My Attempt So far:
SharedPreferences sp = getSharedPreferences("sun32save", MODE_PRIVATE);
SharedPreferences.Editor spedit = sp.edit();
if (spinner1position == 0 & spinner2position == 0) {
spedit.putString("sun32Son", String.valueOf(sonyRs));
String savedValue1 = sp.getString("sun32Son", "");
spedit.commit();
tvSony.setText(savedValue1);
}
//if a value is found, display value
if (spinner1position == 0 & spinner2position == 1) {
spedit.putString("sun35Son", String.valueOf(sonyRs));
String savedValue2 = sp.getString("sun35Son", "");
spedit.commit();
tvSony.setText(savedValue2);
This returns the default value 0 if i go back to the same spinner position.
Screenshot
Edit Error
06-01 18:37:51.503 18264-18264/com.example.liam.quickreport20 E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.liam.quickreport20, PID: 18264
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.liam.quickreport20/com.example.liam.quickreport20.UnitsForm}: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object com.example.liam.quickreport20.UnitsForm$Cache.get(java.lang.Object)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object com.example.liam.quickreport20.UnitsForm$Cache.get(java.lang.Object)' on a null object reference
at com.example.liam.quickreport20.UnitsForm.loadTextFields(UnitsForm.java:220)
at com.example.liam.quickreport20.UnitsForm.onCreate(UnitsForm.java:152)
at android.app.Activity.performCreate(Activity.java:5933)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)