Attempt to invoke virtual method 'internal.policy.DecorView.getWindowInsetsController()' on a null object reference

Question

My application is giving an Error in the opening file. But this bug is only api 30 channel. This is the fault: Attempt to invoke virtual method 'android.view.WindowInsetsController com.android.internal.policy.DecorView.getWindowInsetsController()' on a null object reference

When I put the application in the Goggle Robo test, it gives the following error. But this error occurs only in the api 30s. It works correctly in other apes. I would be glad if you could help. Thank you.

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mobilprogramlar.bilmecebahcesi/com.mobilprogramlar.bilmecebahcesi.AcilisEkrani}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.WindowInsetsController com.android.internal.policy.DecorView.getWindowInsetsController()' on a null object reference
         FATAL EXCEPTION: main
    Process: com.mobilprogramlar.bilmecebahcesi, PID: 13816
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mobilprogramlar.bilmecebahcesi/com.mobilprogramlar.bilmecebahcesi.AcilisEkrani}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.WindowInsetsController com.android.internal.policy.DecorView.getWindowInsetsController()' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3449)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:223)
        at android.app.ActivityThread.main(ActivityThread.java:7656)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
    Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.WindowInsetsController com.android.internal.policy.DecorView.getWindowInsetsController()' on a null object reference
        at com.android.internal.policy.PhoneWindow.getInsetsController(PhoneWindow.java:3880)
        at com.mobilprogramlar.bilmecebahcesi.AcilisEkrani.onCreate(AcilisEkrani.java:18)
        at android.app.Activity.performCreate(Activity.java:8000)
        at android.app.Activity.performCreate(Activity.java:7984)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1309)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3422)
        ... 11 more



java.util.ConcurrentModificationException
     FATAL EXCEPTION: main
Process: com.google.android.googlequicksearchbox:search, PID: 9903
java.util.ConcurrentModificationException
    at java.util.LinkedList$ListItr.checkForComodification(LinkedList.java:966)
    at java.util.LinkedList$ListItr.next(LinkedList.java:888)
    at com.google.android.apps.gsa.shared.util.debug.a.g.a(SourceFile:30)
    at com.google.android.apps.gsa.shared.util.debug.a.g.a(SourceFile:135)
    at com.google.android.apps.gsa.contentprovider.initializer.c.dump(SourceFile:6)
    at android.app.ActivityThread.handleDumpProvider(ActivityThread.java:4307)
    at android.app.ActivityThread.access$2400(ActivityThread.java:237)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2013)
    at android.os.Handler.dispatchMessage(Handler.java:106)
    at android.os.Looper.loop(Looper.java:223)
    at android.app.ActivityThread.main(ActivityThread.java:7656)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)

The opening file is the file with the error.

public class AcilisEkrani extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //requestWindowFeature(Window.FEATURE_NO_TITLE);  
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
            **final WindowInsetsController insetsController = getWindow().getInsetsController();**
            if (insetsController != null) {
                insetsController.hide(WindowInsets.Type.statusBars());
            }
        } else {
            getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
        }
        setContentView(R.layout.acilisekrani);

        // Thread 
        Thread timer = new Thread() {
            @Override
            public void run() {
                try {
                    sleep(1000);    
                } catch (InterruptedException e) {
                    e.printStackTrace();   
                    Log.i("tago","Zamanlayıcı Çalışmadı");
                } finally {
                    Intent i = new Intent(AcilisEkrani.this,UygulamaUrunlerimiz.class);
                    startActivity(i);
                    AcilisEkrani.this.finish();  
                    finish();
                }
            }
        };
        // Thread 
        timer.start();  
    }

    @Override
    protected void onPause() {
        super.onPause();
        finish();       
    }
}

Answer 1

You probably should call setContentView() before you try to access the window. According to official documentation, NullPointerException will only be if the is nothing to render.

Answer 2

put your logic inside => onWindowFocusChanged

    @Override
  public void onWindowFocusChanged(boolean hasFocus) {
    super.onWindowFocusChanged(hasFocus);
    if (hasFocus && Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
      WindowInsetsController controller = getWindow().getInsetsController();
      if(controller != null) {
        controller.setSystemBarsAppearance(WindowInsetsController.APPEARANCE_LIGHT_STATUS_BARS, WindowInsetsController.APPEARANCE_LIGHT_STATUS_BARS);
        // controller.setSystemBarsBehavior(WindowInsetsController.APPEARANCE_LIGHT_STATUS_BARS);
      }
    } else {
      getWindow().getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_STABLE | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN);
      setWindowFlag(this, WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS, false);
      // make fully Android Transparent Status bar
      getWindow().setStatusBarColor(Color.TRANSPARENT);
    }
  }