Puntatore nullo Eccezione in ActionBar

Question

Ricevo questo errore in fase di esecuzione.

java.lang.RuntimeException: Impossibile avviare l'attività ComponentInfo android.util.AndroidRuntimeException: requestFeature() deve essere chiamato prima di aggiungere contenuti

StackTrace:

01-22 04:55:59.728: E/AndroidRuntime(2443): FATAL EXCEPTION: main 
01-22 04:55:59.728: E/AndroidRuntime(2443): Process: com.qrme.quranmadeeasy, PID: 2443 
01-22 04:55:59.728: E/AndroidRuntime(2443): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.qrme.quranmadeeasy/com.qrme.quranmadeeasy.ChapterActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setBackgroundDrawable(android.graphics.drawable.Drawable)' on a null object reference 
01-22 04:55:59.728: E/AndroidRuntime(2443):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298) 
01-22 04:55:59.728: E/AndroidRuntime(2443):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360) 
01-22 04:55:59.728: E/AndroidRuntime(2443):  at android.app.ActivityThread.access$800(ActivityThread.java:144) 
01-22 04:55:59.728: E/AndroidRuntime(2443):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278) 
01-22 04:55:59.728: E/AndroidRuntime(2443):  at android.os.Handler.dispatchMessage(Handler.java:102) 
01-22 04:55:59.728: E/AndroidRuntime(2443):  at android.os.Looper.loop(Looper.java:135) 
01-22 04:55:59.728: E/AndroidRuntime(2443):  at android.app.ActivityThread.main(ActivityThread.java:5221) 
01-22 04:55:59.728: E/AndroidRuntime(2443):  at java.lang.reflect.Method.invoke(Native Method) 
01-22 04:55:59.728: E/AndroidRuntime(2443):  at java.lang.reflect.Method.invoke(Method.java:372) 
01-22 04:55:59.728: E/AndroidRuntime(2443):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899) 
01-22 04:55:59.728: E/AndroidRuntime(2443):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694) 
01-22 04:55:59.728: E/AndroidRuntime(2443): Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setBackgroundDrawable(android.graphics.drawable.Drawable)' on a null object reference 
01-22 04:55:59.728: E/AndroidRuntime(2443):  at com.qrme.quranmadeeasy.ChapterActivity.ActionBar(ChapterActivity.java:212) 
01-22 04:55:59.728: E/AndroidRuntime(2443):  at com.qrme.quranmadeeasy.ChapterActivity.initialize(ChapterActivity.java:112) 
01-22 04:55:59.728: E/AndroidRuntime(2443):  at com.qrme.quranmadeeasy.ChapterActivity.onCreate(ChapterActivity.java:68) 
01-22 04:55:59.728: E/AndroidRuntime(2443):  at android.app.Activity.performCreate(Activity.java:5933) 
01-22 04:55:59.728: E/AndroidRuntime(2443):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105) 
01-22 04:55:59.728: E/AndroidRuntime(2443):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251) 
01-22 04:55:59.728: E/AndroidRuntime(2443):  ... 10 more 

Modificato:

ChapterActivity.java:

import android.support.v7.app.ActionBarActivity; 

public class ChapterActivity extends ActionBarActivity implements OnItemClickListener { 

@Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
    // requestWindowFeature(Window.FEATURE_ACTION_BAR); 
     setContentView(R.layout.activity_chapter); 

     initialize(); --->68th line 
} 
private void initialize() { 

    listChapter.setDivider(new ColorDrawable(Color 
       .parseColor(separator_grey))); 
     listChapter.setDividerHeight(2); 
    ............ 

    ActionBar(); -->112th line 
    } 

public void ActionBar() { 
     ActionBar actionBar = getActionBar(); 
     actionBar.setBackgroundDrawable(new ColorDrawable(Color --->212th line 
       .parseColor(white))); 
     actionBar.setDisplayShowHomeEnabled(false); 
     actionBar.setDisplayShowTitleEnabled(false); 
     LayoutInflater mInflater = LayoutInflater.from(this); 

     ......... 
     actionBar.setCustomView(mCustomView); 
     actionBar.setDisplayShowCustomEnabled(true); 
    } 
} 

styles.xml:

<resources> 

    <style name="AppBaseTheme" parent="@style/Theme.AppCompat"></style> 

    <!-- Application theme. --> 
    <style name="AppTheme" parent="AppBaseTheme"> 
     <!-- All customizations that are NOT specific to a particular API-level can go here. --> 
    </style> 
</resources> 

manifesto:

<application 
     android:name="com.qrme.quranmadeeasy.Application" 
     android:allowBackup="true" 
     android:icon="@drawable/ic_launcher" 
     android:label="@string/app_name" 
     android:theme="@style/AppTheme" > 
     <activity 
      android:name=".MainActivity" 
      android:label="@string/app_name" 
      android:screenOrientation="portrait"    
       > 
      <intent-filter> 
       <action android:name="android.intent.action.MAIN" /> 

       <category android:name="android.intent.category.LAUNCHER" /> 
      </intent-filter> 
     </activity> 
    ........ 
    <application> 

non sapevo come risolvere this.Anyone può aiutami con questo.Grazie.

Answer 1

rimuovere la linea

requestWindowFeature(Window.FEATURE_ACTION_BAR); 

Non è necessario quando si utilizza Theme.AppCompat (che aggiunge la propria azione Bar). Assicurati inoltre che l'attività sia estesa a ActionBarActivity (come richiesto da Theme.AppCompat) anziché a Activity.

Quando si utilizza ActionBarActivity, è necessario utilizzare anche getSupportActionBar() anziché getActionBar().

Answer 2

Linea 212

Sbagliato:ColorDrawable(Color.parseColor(white));

corretta:ColorDrawable(Color.parseColor("#FFFFFF"));