如何在android中的操作欄中設置自定義視圖？

Question

我想在操作欄應用程序標題中使用自定義字體，但每次遇到同樣的錯誤（空指針異常），我的應用程序都會對我說「Unfortunately **** has stopped」。我搜查了很多並試圖使用它們。但沒有工作。同樣的錯誤不斷髮生。我創建了一個簡單的佈局，一個TextView，並試圖通過這條線

ActionBar actionBar = getActionBar(); 
actionBar.setCustomView(R.layout.custom_actionbar); 

無論我做什麼，在setCustomView送我的空指針錯誤插入的動作條。我在想，如果我可以在操作欄中設置佈局，將很容易改變TextView字體。這是我的完整代碼。

public class MainActivity extends ActionBarActivity { 
    @TargetApi(Build.VERSION_CODES.HONEYCOMB) 
    @Override 
    protected void onCreate(Bundle savedInstanceState) { 

     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 

     ViewPager viewPager = (ViewPager) findViewById(R.id.pager); 
     viewPager.setAdapter(new ViewPagerAdapter(getSupportFragmentManager())); 
     ActionBar actionBar = getActionBar(); 
     actionBar.setCustomView(R.layout.custom_actionbar); 

    } 
} 

和佈局

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:background="@android:color/transparent" > 

    <TextView 
     android:id="@+id/App_title" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_centerVertical="true" 
     android:layout_marginLeft="10dp" 
     android:textSize="40dp" 
     android:maxLines="2" 
     android:ellipsize="end" 
     android:text="Prime" /> 
</RelativeLayout> 

和錯誤：

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.tushar.primeplay2/com.example.tushar.primeplay2.MainActivity}: java.lang.NullPointerException 
      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2306) 
      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2358) 
      at android.app.ActivityThread.access$600(ActivityThread.java:156) 
      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1340) 
      at android.os.Handler.dispatchMessage(Handler.java:99) 
      at android.os.Looper.loop(Looper.java:153) 
      at android.app.ActivityThread.main(ActivityThread.java:5297) 
      at java.lang.reflect.Method.invokeNative(Native Method) 
      at java.lang.reflect.Method.invoke(Method.java:511) 
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833) 
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600) 
      at dalvik.system.NativeStart.main(Native Method) 
    Caused by: java.lang.NullPointerException 
      at com.example.tushar.primeplay2.MainActivity.onCreate(MainActivity.java:22) 
      at android.app.Activity.performCreate(Activity.java:5122) 
      at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1081) 
      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2270) 
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2358) 
            at android.app.ActivityThread.access$600(ActivityThread.java:156) 
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1340) 
            at android.os.Handler.dispatchMessage(Handler.java:99) 
            at android.os.Looper.loop(Looper.java:153) 
            at android.app.ActivityThread.main(ActivityThread.java:5297) 
            at java.lang.reflect.Method.invokeNative(Native Method) 
            at java.lang.reflect.Method.invoke(Method.java:511) 
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833) 
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600) 
            at dalvik.system.NativeStart.main(Native Method) 

我使用Android的工作室。

Answer 1

試試這個

如果您正在使用支持庫

ActionBar actionBar = getActionBar(); 

否則

ActionBar actionBar = getSupportActionBar(); 

然後

LayoutInflater inflator = (LayoutInflater) this .getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
View v = inflator.inflate(R.layout.custom_actionbar, null); 
actionBar.setCustomView(v); 

你onCreate看起來應該如T他

public class MainActivity extends ActionBarActivity { 
@TargetApi(Build.VERSION_CODES.HONEYCOMB) 
@Override 
protected void onCreate(Bundle savedInstanceState) { 

    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 

    ViewPager viewPager = (ViewPager) findViewById(R.id.pager); 
    viewPager.setAdapter(new ViewPagerAdapter(getSupportFragmentManager())); 
    ActionBar actionBar = getSupportActionBar(); // As you said you are using support library 
    LayoutInflater inflator = (LayoutInflater) this .getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
    View v = inflator.inflate(R.layout.custom_actionbar, null); 
    actionBar().setDisplayOptions(ActionBar.DISPLAY_SHOW_CUSTOM); 
    actionBar.setCustomView(v); 

} 
} 

記住

import android.support.v7.app.ActionBar 

而不是

import android.app.ActionBar