使imageview不可見的原因NullPointerException

我正在運行下面的代碼，它給了我在行iv4.setVisibility（View.INVISIBLE） NullPointerException請建議。感謝代碼：使imageview不可見的原因NullPointerException

ImageView iv4; 
    public void onCreate(Bundle savedInstanceState) { 
      requestWindowFeature(Window.FEATURE_NO_TITLE); 
      getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, 
      WindowManager.LayoutParams.FLAG_FULLSCREEN); 
      super.onCreate(savedInstanceState); 
      setContentView(R.layout.activity_score); 
      iv4= (ImageView) findViewById(R.id.imageView4); 
      iv4.setVisibility(View.INVISIBLE); 
     } 

<RelativeLayout 
    xmlns:android="schemas.android.com/apk/res/android"; 
    android:id="@+id/RelativeLayout1" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent"> 

<ImageView android:id="@+id/imageView4" 
     android:layout_width="110dp" 
     android:layout_height="110dp" 
     android:layout_alignParentRight="true" 
     android:layout_alignParentTop="true" 
     android:src="@drawable/hg" /> 
    </RelativeLayout>

堆棧跟蹤如下：

03-05 03:49:25.477: E/AndroidRuntime(1070): FATAL EXCEPTION: main 
03-05 03:49:25.477: E/AndroidRuntime(1070): java.lang.RuntimeException: Unable to start activity ComponentInfo{bitcream.candyhive.candy/bitcream.candyhive.candy.ScoreActivity}: java.lang.NullPointerException 
03-05 03:49:25.477: E/AndroidRuntime(1070):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647) 
03-05 03:49:25.477: E/AndroidRuntime(1070):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663) 
03-05 03:49:25.477: E/AndroidRuntime(1070):  at android.app.ActivityThread.access$1500(ActivityThread.java:117) 
03-05 03:49:25.477: E/AndroidRuntime(1070):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931) 
03-05 03:49:25.477: E/AndroidRuntime(1070):  at android.os.Handler.dispatchMessage(Handler.java:99) 
03-05 03:49:25.477: E/AndroidRuntime(1070):  at android.os.Looper.loop(Looper.java:123) 
03-05 03:49:25.477: E/AndroidRuntime(1070):  at android.app.ActivityThread.main(ActivityThread.java:3683) 
03-05 03:49:25.477: E/AndroidRuntime(1070):  at java.lang.reflect.Method.invokeNative(Native Method) 
03-05 03:49:25.477: E/AndroidRuntime(1070):  at java.lang.reflect.Method.invoke(Method.java:507) 
03-05 03:49:25.477: E/AndroidRuntime(1070):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 
03-05 03:49:25.477: E/AndroidRuntime(1070):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 
03-05 03:49:25.477: E/AndroidRuntime(1070):  at dalvik.system.NativeStart.main(Native Method) 
03-05 03:49:25.477: E/AndroidRuntime(1070): Caused by: java.lang.NullPointerException 
03-05 03:49:25.477: E/AndroidRuntime(1070):  at bitcream.candyhive.candy.ScoreActivity.onCreate(ScoreActivity.java:42) 
03-05 03:49:25.477: E/AndroidRuntime(1070):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 
03-05 03:49:25.477: E/AndroidRuntime(1070):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611) 
03-05 03:49:25.477: E/AndroidRuntime(1070):  ... 11 more 
03-05 03:49:28.297: I/Process(1070): Sending signal. PID: 1070 SIG: 9

來源

2014-03-05 Shubhankar

post'activity_score.xml' – Raghunandan

這個問題看起來有點傻......你在'activity_score.xml'裏面聲明瞭'R.id.imageView4'嗎？ – Blackbelt

是的，我這樣做了......但仍顯示相同的... !!! – Shubhankar

的NullPointerException在線路iv4.setVisibility（View.INVISIBLE）

大概沒有ImageView與編號imageView4在activity_score.xml。

要麼你引用錯誤的佈局，要麼你的佈局不包含帶有上述id的imageview。

編輯：

變化

<RelativeLayout 
xmlns:android="schemas.android.com/apk/res/android"

到

<RelativeLayout 
xmlns:android="http://schemas.android.com/apk/res/android"

您將獲得NullPointerException如果findViewById沒有找到與當前膨脹的佈局中提到的ID的視圖。

來源

2014-03-05 13:56:26 Raghunandan

使imageview不可見的原因NullPointerException

回答

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