在MediaFile應用程序中處理異常

我正在開發一個媒體文件應用程序，用於播放存儲在我的原始文件夾中的中的聲音。總共有大約32種聲音。這就是我做上的每個按鈕的點擊：在MediaFile應用程序中處理異常

Button btnGrowUp = (Button) this.findViewById(R.id.GrowUp); 
btnGrowUp.setOnClickListener(btnGrowUpListener); 

private OnClickListener btnGrowUpListener = new OnClickListener() 
{ 
    public void onClick(View v) 
    { 
     //Toast.makeText(getBaseContext(), "Grow Up audio file is being played", Toast.LENGTH_SHORT).show(); 

     MediaPlayer mp = MediaPlayer.create(MainScreen.this, R.raw.growup); 
     mp.start(); 
    } 
};

我得到一個運行時異常說：「應用程序意外終止」在我的logcat窗口如下消息：

12-19 12:33:05.420: WARN/dalvikvm(699): threadid=3: thread exiting 
with uncaught exception (group=0x4000fe70) 
12-19 12:33:05.441: ERROR/AndroidRuntime(699): Uncaught handler: 
thread main exiting due to uncaught exception 
12-19 12:33:05.460: ERROR/AndroidRuntime(699): 
java.lang.NullPointerException 
12-19 12:33:05.460: ERROR/AndroidRuntime(699):  at 
com.myapps.media.MainScreen$8.onClick(MainScreen.java:244) 
12-19 12:33:05.460: ERROR/AndroidRuntime(699):  at 
android.view.View.performClick(View.java:2179) 
12-19 12:33:05.460: ERROR/AndroidRuntime(699):  at 
android.view.View.onTouchEvent(View.java:3828) 
12-19 12:33:05.460: ERROR/AndroidRuntime(699):  at 
android.widget.TextView.onTouchEvent(TextView.java:6291) 
12-19 12:33:05.460: ERROR/AndroidRuntime(699):  at 
android.view.View.dispatchTouchEvent(View.java:3368) 
12-19 12:33:05.460: ERROR/AndroidRuntime(699):  at 
android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:863) 
12-19 12:33:05.460: ERROR/AndroidRuntime(699):  at 
android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:863) 
12-19 12:33:05.460: ERROR/AndroidRuntime(699):  at 
android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:863) 
12-19 12:33:05.460: ERROR/AndroidRuntime(699):  at 
android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:863) 
12-19 12:33:05.460: ERROR/AndroidRuntime(699):  at 
android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:863) 
12-19 12:33:05.460: ERROR/AndroidRuntime(699):  at 
com.android.internal.policy.impl.PhoneWindow 
$DecorView.superDispatchTouchEvent(PhoneWindow.java:1707) 
12-19 12:33:05.460: ERROR/AndroidRuntime(699):  at 
com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent 
(PhoneWindow.java:1197) 
12-19 12:33:05.460: ERROR/AndroidRuntime(699):  at 
android.app.Activity.dispatchTouchEvent(Activity.java:1993) 
12-19 12:33:05.460: ERROR/AndroidRuntime(699):  at 
com.android.internal.policy.impl.PhoneWindow 
$DecorView.dispatchTouchEvent(PhoneWindow.java:1691) 
12-19 12:33:05.460: ERROR/AndroidRuntime(699):  at 
android.view.ViewRoot.handleMessage(ViewRoot.java:1525) 
12-19 12:33:05.460: ERROR/AndroidRuntime(699):  at 
android.os.Handler.dispatchMessage(Handler.java:99) 
12-19 12:33:05.460: ERROR/AndroidRuntime(699):  at 
android.os.Looper.loop(Looper.java:123) 
12-19 12:33:05.460: ERROR/AndroidRuntime(699):  at 
android.app.ActivityThread.main(ActivityThread.java:3948) 
12-19 12:33:05.460: ERROR/AndroidRuntime(699):  at 
java.lang.reflect.Method.invokeNative(Native Method) 
12-19 12:33:05.460: ERROR/AndroidRuntime(699):  at 
java.lang.reflect.Method.invoke(Method.java:521) 
12-19 12:33:05.460: ERROR/AndroidRuntime(699):  at 
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run 
(ZygoteInit.java:782) 
12-19 12:33:05.460: ERROR/AndroidRuntime(699):  at 
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:540) 
12-19 12:33:05.460: ERROR/AndroidRuntime(699):  at 
dalvik.system.NativeStart.main(Native Method) 
12-19 12:33:05.520: INFO/Process(563): Sending signal. PID: 699 SIG: 3 
12-19 12:33:05.520: INFO/dalvikvm(699): threadid=7: reacting to signal 
3 
12-19 12:33:05.601: INFO/dalvikvm(699): Wrote stack trace to '/data/ 
anr/traces.txt' 
12-19 12:33:05.982: INFO/ARMAssembler(563): generated 
scanline__00000077:03515104_00000000_00000000 [ 27 ipp] (41 ins) at 
[0x27c718:0x27c7bc] in 982527 ns 
12-19 12:33:06.011: INFO/ARMAssembler(563): generated 
scanline__00000077:03515104_00001001_00000000 [ 64 ipp] (84 ins) at 
[0x27c7c0:0x27c910] in 1804978 ns

如何解決此問題？謝謝

Maqsood

來源

2009-12-20 Muhammad Maqsoodur Rehman

因爲在你的代碼清單中沒有行號，所以如果你讓我們知道哪一行失敗，這將非常有用！（或使用餡餅，我猜上下文很重要） – moritz 2009-12-30 02:32:24

順便說一句，MainScreen.this？ – moritz 2009-12-30 02:34:02

正在定義的匿名監聽器（'btnGrowUpListener'）被封裝在名爲'MainScreen'的類中，因此爲了提供Android'Context'需要，使用'MainScreen.this'表示法。 – 2009-12-31 01:14:19

爲MediaPlayer constructor您正在使用的Javadoc說，它會返回null如果玩家的創建失敗。

在調用start方法之前，您不檢查創建是否成功，因此根據上面的堆棧跟蹤，這是導致您看到異常的最可能原因。

來源

2009-12-30 02:32:42

非常感謝！我已經整理出來了。 – 2009-12-30 20:03:15

在MediaFile應用程序中處理異常

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