NullPointerException con ProgressBar utilizzando ActionBarCompat

Question

Utilizzo ActionBarCompat in support-v7-r18. Quando si tenta di mostrare un progresso indeterminato, funziona su Galaxy S3 Android 4.1.2 ma non su Galaxy Ace Android 2.3.3.

Non riesco a capire perché.

Il codice sollevando l'eccezione:

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    ... 
    final ActionBarActivity activity = this; 
    content = (WebView) findViewById(R.id.webContent); 
    content.setWebViewClient(new WebViewClient() { 
     @Override 
     public void onPageStarted(WebView view, String url, Bitmap favicon) { 
      super.onPageStarted(view, url, favicon); 
      activity.setSupportProgressBarIndeterminate(true); <=== Line 88 
      activity.setSupportProgressBarIndeterminateVisibility(true); 
     } 
    } 

L'eccezione:

FATAL EXCEPTION: main 
    java.lang.NullPointerException 
    at android.support.v7.app.ActionBarActivityDelegateBase.updateProgressBars(ActionBarActivityDelegateBase.java:508) 
    at android.support.v7.app.ActionBarActivityDelegateBase.setSupportProgressBarIndeterminate(ActionBarActivityDelegateBase.java:469) 
    at android.support.v7.app.ActionBarActivity.setSupportProgressBarIndeterminate(ActionBarActivity.java:282) 
    at MyActivity.onPageStarted(MyActivityActivity.java:88) 
    at android.webkit.CallbackProxy.handleMessage(CallbackProxy.java:266) 
    at android.os.Handler.dispatchMessage(Handler.java:99) 
    at android.os.Looper.loop(Looper.java:123) 
    at android.app.ActivityThread.main(ActivityThread.java:3687) 
    at java.lang.reflect.Method.invokeNative(Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:507) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625) 
    at dalvik.system.NativeStart.main(Native Method) 

Answer 1

Aggiungi supportRequestWindowFeature(Window.FEATURE_PROGRESS); o supportRequestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS); per onCreate metodo() prima di chiamare setContentView().