無法顯示警報對話框

我無法顯示警報對話框。一切都是正確的，直到我設置方法dialog.show（），然後我無法打開我的應用程序。沒有這個方法一切都很好。無法顯示警報對話框

我聲明瞭兩個全局對象：

AlertDialog.Builder builder; 
AlertDialog dialog;

然後在MainActivity，我建立由建設者的對話，並創建它。

builder = new AlertDialog.Builder(this.getApplicationContext()); 
     builder.setMessage("We're sorry, but on Your device accelerometer isn't available") 
     .setCancelable(false) 
     .setPositiveButton("OK", new DialogInterface.OnClickListener() { 

      @Override 
      public void onClick(DialogInterface dialog, int which) 
      { 
       MainActivity.this.finish(); 
      } 
     }); 

     dialog = builder.create();

這一刻一切正常，並沒有任何異常，但是當我要顯示的對話框中，一些例外情況出現，我無法運行此應用程序：

dialog.show(); //this method doesn't work and causes problems

我做了什麼錯誤？

編輯：例外：

06-26 20:49:03.540: D/dalvikvm(4085): GC_FOR_ALLOC freed 38K, 8% free 2499K/2712K, paused 42ms, total 45ms 
06-26 20:49:03.580: I/dalvikvm-heap(4085): Grow heap (frag case) to 6.146MB for 3712016-byte allocation 
06-26 20:49:03.700: D/dalvikvm(4085): GC_FOR_ALLOC freed 2K, 4% free 6121K/6340K, paused 112ms, total 112ms 
06-26 20:49:03.770: D/dalvikvm(4085): GC_CONCURRENT freed <1K, 4% free 6121K/6340K, paused 6ms+16ms, total 71ms 
06-26 20:49:04.460: D/gralloc_goldfish(4085): Emulator without GPU emulation detected. 
06-26 20:49:42.030: E/Trace(4138): error opening trace file: No such file or directory (2) 
06-26 20:49:42.900: D/dalvikvm(4138): GC_FOR_ALLOC freed 41K, 8% free 2499K/2716K, paused 66ms, total 68ms 
06-26 20:49:42.940: I/dalvikvm-heap(4138): Grow heap (frag case) to 6.146MB for 3712016-byte allocation 
06-26 20:49:43.050: D/dalvikvm(4138): GC_FOR_ALLOC freed 2K, 4% free 6121K/6344K, paused 107ms, total 107ms 
06-26 20:49:43.120: D/dalvikvm(4138): GC_CONCURRENT freed <1K, 4% free 6121K/6344K, paused 5ms+5ms, total 70ms 
06-26 20:49:43.540: D/dalvikvm(4138): GC_FOR_ALLOC freed 3638K, 53% free 3483K/7300K, paused 36ms, total 37ms 
06-26 20:49:43.621: D/AndroidRuntime(4138): Shutting down VM 
06-26 20:49:43.630: W/dalvikvm(4138): threadid=1: thread exiting with uncaught exception (group=0x40a71930) 
06-26 20:49:43.640: E/AndroidRuntime(4138): FATAL EXCEPTION: main 
06-26 20:49:43.640: E/AndroidRuntime(4138): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.accelerometertest/com.example.accelerometertest.MainActivity}: android.view.WindowManager$BadTokenException: Unable to add window -- token null is not for an application 
06-26 20:49:43.640: E/AndroidRuntime(4138):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180) 
06-26 20:49:43.640: E/AndroidRuntime(4138):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230) 
06-26 20:49:43.640: E/AndroidRuntime(4138):  at android.app.ActivityThread.access$600(ActivityThread.java:141) 
06-26 20:49:43.640: E/AndroidRuntime(4138):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234) 
06-26 20:49:43.640: E/AndroidRuntime(4138):  at android.os.Handler.dispatchMessage(Handler.java:99) 
06-26 20:49:43.640: E/AndroidRuntime(4138):  at android.os.Looper.loop(Looper.java:137) 
06-26 20:49:43.640: E/AndroidRuntime(4138):  at android.app.ActivityThread.main(ActivityThread.java:5041) 
06-26 20:49:43.640: E/AndroidRuntime(4138):  at java.lang.reflect.Method.invokeNative(Native Method) 
06-26 20:49:43.640: E/AndroidRuntime(4138):  at java.lang.reflect.Method.invoke(Method.java:511) 
06-26 20:49:43.640: E/AndroidRuntime(4138):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 
06-26 20:49:43.640: E/AndroidRuntime(4138):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 
06-26 20:49:43.640: E/AndroidRuntime(4138):  at dalvik.system.NativeStart.main(Native Method) 
06-26 20:49:43.640: E/AndroidRuntime(4138): Caused by: android.view.WindowManager$BadTokenException: Unable to add window -- token null is not for an application 
06-26 20:49:43.640: E/AndroidRuntime(4138):  at android.view.ViewRootImpl.setView(ViewRootImpl.java:571) 
06-26 20:49:43.640: E/AndroidRuntime(4138):  at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:246) 
06-26 20:49:43.640: E/AndroidRuntime(4138):  at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:69) 
06-26 20:49:43.640: E/AndroidRuntime(4138):  at android.app.Dialog.show(Dialog.java:281) 
06-26 20:49:43.640: E/AndroidRuntime(4138):  at com.example.accelerometertest.MainActivity.onCreate(MainActivity.java:67) 
06-26 20:49:43.640: E/AndroidRuntime(4138):  at android.app.Activity.performCreate(Activity.java:5104) 
06-26 20:49:43.640: E/AndroidRuntime(4138):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080) 
06-26 20:49:43.640: E/AndroidRuntime(4138):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144) 
06-26 20:49:43.640: E/AndroidRuntime(4138):  ... 11 more

來源

2013-06-26 user2511941

你能後的異常？ – Rob013

您不應該使用應用程序上下文來創建對話框。如果你在一個活動中，然後使用它作爲你的上下文。 –

爲什麼要將構建器和對話框聲明爲「全局對象」？只需在需要時使用局部變量創建並顯示對話框。 –

變化

builder = new AlertDialog.Builder(this.getApplicationContext());

到（只要this是您的MainActivity）

builder = new AlertDialog.Builder(this);

來源

2013-06-26 21:07:46 petey

無法顯示警報對話框

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