无法显示警报对话框

我无法显示警报对话框。一切都是正确的，直到我设置方法dialog.show（），然后我无法打开我的应用程序。没有这个方法一切都很好。无法显示警报对话框

我声明了两个全局对象：

AlertDialog.Builder builder; 
AlertDialog dialog;

然后在MainActivity，我建立由建设者的对话，并创建它。

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();

这一刻一切正常，并没有任何异常，但是当我要显示的对话框中，一些例外情况出现，我无法运行此应用程序：

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

我做了什么错误？

编辑：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

来源

2013-06-26 user2511941

你能后的异常？ – Rob013

您不应该使用应用程序上下文来创建对话框。如果你在一个活动中，然后使用它作为你的上下文。 –

为什么要将构建器和对话框声明为“全局对象”？只需在需要时使用局部变量创建并显示对话框。 –

变化

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

到（只要this是您的MainActivity）

builder = new AlertDialog.Builder(this);

来源

2013-06-26 21:07:46 petey

无法显示警报对话框

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