獲取異常而轉換的LinearLayout圖像

我要轉換的LinearLayout到image.I我爲此目的可以使用下面的代碼，但我正在逐漸nullpointerexception.Please告訴我怎麼解決這個problem.This代碼如下：獲取異常而轉換的LinearLayout圖像

public class AndroidWebImage extends Activity { 

ImageView bmImage; 
LinearLayout view; 
    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.main); 

     view = (LinearLayout)findViewById(R.id.screen); 
     bmImage = (ImageView)findViewById(R.id.image); 

     view.setDrawingCacheEnabled(true); 
     // this is the important code :) 
     // Without it the view will have a dimension of 0,0 and the bitmap will be null   

     view.measure(MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED), 
      MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED)); 

     view.layout(0, 0, view.getMeasuredWidth(), view.getMeasuredHeight()); 

     view.buildDrawingCache(true); 
     Bitmap b = Bitmap.createBitmap(view.getDrawingCache()); 
     view.setDrawingCacheEnabled(false); // clear drawing cache 

     bmImage.setImageBitmap(b); 

}; 
}

我在這一行越來越異常：

Bitmap b = Bitmap.createBitmap(view.getDrawingCache());

這是錯誤日誌：

09-13 12:19:26.061: W/dalvikvm(551): threadid=3: thread exiting with uncaught exception (group=0x4001b188) 
09-13 12:19:26.112: E/AndroidRuntime(551): Uncaught handler: thread main exiting due to uncaught exception 
09-13 12:19:26.593: E/AndroidRuntime(551): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.velosys.interview_preparation/com.velosys.interview_preparation.activities.Certificate}: java.lang.NullPointerException 
09-13 12:19:26.593: E/AndroidRuntime(551): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2496) 
09-13 12:19:26.593: E/AndroidRuntime(551): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2512) 
09-13 12:19:26.593: E/AndroidRuntime(551): at android.app.ActivityThread.access$2200(ActivityThread.java:119) 
09-13 12:19:26.593: E/AndroidRuntime(551): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1863) 
09-13 12:19:26.593: E/AndroidRuntime(551): at android.os.Handler.dispatchMessage(Handler.java:99) 
09-13 12:19:26.593: E/AndroidRuntime(551): at android.os.Looper.loop(Looper.java:123) 
09-13 12:19:26.593: E/AndroidRuntime(551): at android.app.ActivityThread.main(ActivityThread.java:4363) 
09-13 12:19:26.593: E/AndroidRuntime(551): at java.lang.reflect.Method.invokeNative(Native Method) 
09-13 12:19:26.593: E/AndroidRuntime(551): at java.lang.reflect.Method.invoke(Method.java:521) 
09-13 12:19:26.593: E/AndroidRuntime(551): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860) 
09-13 12:19:26.593: E/AndroidRuntime(551): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618) 
09-13 12:19:26.593: E/AndroidRuntime(551): at dalvik.system.NativeStart.main(Native Method) 
09-13 12:19:26.593: E/AndroidRuntime(551): Caused by: java.lang.NullPointerException 
09-13 12:19:26.593: E/AndroidRuntime(551): at android.graphics.Bitmap.createBitmap(Bitmap.java:358) 
09-13 12:19:26.593: E/AndroidRuntime(551): at com.velosys.interview_preparation.activities.Certificate.onCreate(Certificate.java:76) 
09-13 12:19:26.593: E/AndroidRuntime(551): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 
09-13 12:19:26.593: E/AndroidRuntime(551): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2459) 
09-13 12:19:26.593: E/AndroidRuntime(551): ... 11 more 
09-13 12:19:26.661: I/dalvikvm(551): threadid=7: reacting to signal 3 
09-13 12:19:26.661: E/dalvikvm(551): Unable to open stack trace file '/data/anr/traces.txt': Permission denied

提前致謝。

來源

2012-09-13 user1662334

請問您可以發佈日誌。 – Flo

我先生也粘貼了日誌。 – user1662334

你不能在onCreate中做到這一點。該佈局尚未顯示。稍後您可以在Activity的lifecylce中執行此操作，例如onWindowFocusChanged或使用ViewTreeObserver，我更喜歡它，因爲它更符合OOP。

http://developer.android.com/reference/android/view/ViewTreeObserver.OnGlobalLayoutListener.html

來源

2012-09-13 09:01:08 Simon

感謝它的工作。 – user1662334

古怪繪圖緩存似乎返回空的getDrawingCache（）。

也許你可以試試這個方法，而無需使用的緩存。

Bitmap bitmap = Bitmap.createBitmap(view.getLayoutParams().width, view.getLayoutParams().height, Bitmap.Config.ARGB_8888);     
Canvas canvas = new Canvas(bitmap); 
view.layout(0, 0, view.getLayoutParams().width, view.getLayoutParams().height); 
view.draw(canvas);

來源

2012-09-13 08:21:41 Flo

對不起，先生，這不是解決問題。 – user1662334

獲取異常而轉換的LinearLayout圖像

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