Исключение Null pointer в android.app.actionbar

Question

Я получаю исключение нулевого указателя во время выполнения. Я указал строку ошибки в приведенном ниже коде.

Я получаю эту ошибку:

java.lang.RuntimeException: Unable to start activity java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setHomeButtonEnabled(boolean)' on a null object reference

StackTrace:

01-21 11:12:12.060: E/AndroidRuntime(2102):  at android.app.ActivityThread.access$800(ActivityThread.java:144) 
01-21 11:22:37.975: E/AndroidRuntime(2176): FATAL EXCEPTION: main 
01-21 11:22:37.975: E/AndroidRuntime(2176): Process: com.qrme.quranmadeeasy, PID: 2176 
01-21 11:22:37.975: E/AndroidRuntime(2176): 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.setDisplayHomeAsUpEnabled(boolean)' on a null object reference 
01-21 11:22:37.975: E/AndroidRuntime(2176):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298) 
01-21 11:22:37.975: E/AndroidRuntime(2176):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360) 
01-21 11:22:37.975: E/AndroidRuntime(2176):  at android.app.ActivityThread.access$800(ActivityThread.java:144) 
01-21 11:22:37.975: E/AndroidRuntime(2176):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278) 
01-21 11:22:37.975: E/AndroidRuntime(2176):  at android.os.Handler.dispatchMessage(Handler.java:102) 
01-21 11:22:37.975: E/AndroidRuntime(2176):  at android.os.Looper.loop(Looper.java:135) 
01-21 11:22:37.975: E/AndroidRuntime(2176):  at android.app.ActivityThread.main(ActivityThread.java:5221) 
01-21 11:22:37.975: E/AndroidRuntime(2176):  at java.lang.reflect.Method.invoke(Native Method) 
01-21 11:22:37.975: E/AndroidRuntime(2176):  at java.lang.reflect.Method.invoke(Method.java:372) 
01-21 11:22:37.975: E/AndroidRuntime(2176):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899) 
01-21 11:22:37.975: E/AndroidRuntime(2176):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694) 
01-21 11:22:37.975: E/AndroidRuntime(2176): Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setDisplayHomeAsUpEnabled(boolean)' on a null object reference 
01-21 11:22:37.975: E/AndroidRuntime(2176):  at com.qrme.quranmadeeasy.ChapterActivity.onCreate(ChapterActivity.java:64) 
01-21 11:22:37.975: E/AndroidRuntime(2176):  at android.app.Activity.performCreate(Activity.java:5933) 
01-21 11:22:37.975: E/AndroidRuntime(2176):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105) 
01-21 11:22:37.975: E/AndroidRuntime(2176):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251) 
01-21 11:22:37.975: E/AndroidRuntime(2176):  ... 10 more 

ChapterActivity.java:

public class ChapterActivity extends Activity implements OnItemClickListener { 

@Override 
    protected void onCreate(Bundle savedInstanceState) { 

     super.onCreate(savedInstanceState); 
     getWindow().requestFeature(Window.FEATURE_ACTION_BAR); 
     setContentView(R.layout.activity_chapter); 

     getActionBar().setDisplayHomeAsUpEnabled(true); --->64th line error 
     getActionBar().setHomeButtonEnabled(true); 

     initialize(); 
     listChapter.setOnItemClickListener(this); 
    } 

private void initialize() { 

..... 
.... 
ActionBar(); 
} 

public void ActionBar() { 
     ActionBar mActionBar = getActionBar(); 
     mActionBar.setBackgroundDrawable(new ColorDrawable(Color 
       .parseColor(white))); 
     mActionBar.setDisplayShowHomeEnabled(false); 
     mActionBar.setDisplayShowTitleEnabled(false); 
     LayoutInflater mInflater = LayoutInflater.from(this); 

     View mCustomView = mInflater.inflate(R.layout.custom_actionbar, null); 

     Typeface type = Typeface.createFromAsset(getAssets(), 
       "Roboto-Medium.ttf"); 

     TextView mTitleTextView = (TextView) mCustomView 
       .findViewById(R.id.textviewHeading); 
     mTitleTextView.setTypeface(type); 

     ImageButton imgbuttonSettings = (ImageButton) mCustomView 
       .findViewById(R.id.imagebuttonSettings); 
     ImageButton imgbuttonPre = (ImageButton) mCustomView 
       .findViewById(R.id.imagebuttonPre); 
     imgbuttonPre.setVisibility(View.GONE); 
     imgbuttonSettings.setOnClickListener(new OnClickListener() { 

      @Override 
      public void onClick(View view) { 
       startActivity(new Intent(ChapterActivity.this, 
         SettingsActivity.class)); 
      } 
     }); 

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

Manifest:

<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" 
      android:theme="@android:style/Theme.Translucent.NoTitleBar.Fullscreen" 

       > 
      <intent-filter> 
       <action android:name="android.intent.action.MAIN" /> 

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

Любой может помочь мне с этой проблемой. Благодарю вас.

Answer 1

Удалите эту строку из вашего файла манифеста

android:theme="@android:style/Theme.Translucent.NoTitleBar.Fullscreen" 

это указывает на полный экран не означает, что нет строки заголовка, ни действий бар, так что вы получаете NPE.

EDIT:

также переместить эту строку в Actionbar() функции

getActionBar().setDisplayHomeAsUpEnabled(true); 
getActionBar().setHomeButtonEnabled(true); 

public void ActionBar() { 
    ActionBar mActionBar = getActionBar(); 
    mActionBar.setDisplayHomeAsUpEnabled(true); 
    mActionBar.setHomeButtonEnabled(true); 
}