android - 从非 Activity 中完成 Activity

Question

我正在开发一个应用程序。我想从第一个 Activity 中调用一个警报对话框。警报对话框是在另一个类中编写的，该类是非 Activity 类。应用程序的需要是调用 Activity 应该从编写在非 Activity 类中的警报结束。调用警报的代码如下。

从第一个 Activity 调用警报:

public class Activity1 extends Activity {
    /** Called when the activity is first created. */
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.list_layout);
    }// End of onCreate.

        /** Back Button. */
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            String message = "Do you Want to Exit.";
            Utility.callAlert(message, getApplicationContext());
            return true;
        }
        return super.onKeyDown(keyCode, event);
    }   
}

具有警告对话框的被调用类是:

public class Utility {
    // callAlert method to display alert, when exception occur.
    public static void callAlert(String message, final Context context){
        AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(context);
        alertDialogBuilder.setTitle("MyApplication.");
        alertDialogBuilder.setMessage(message);
        alertDialogBuilder.setNeutralButton("Ok", new DialogInterface.OnClickListener() {                   

            public void onClick(DialogInterface dialog, int which) {
                ((Activity1)context.getApplicationContext()).finish();
            } //end onClick.
        }); // end alertDialog.setButton.
        alertDialogBuilder.show();  
    }
}

但这给我的错误是:

02-25 17:00:45.961: D/AndroidRuntime(444): Shutting down VM
02-25 17:00:45.961: W/dalvikvm(444): threadid=1: thread exiting with uncaught exception (group=0x40015560)
02-25 17:00:45.971: E/AndroidRuntime(444): FATAL EXCEPTION: main
02-25 17:00:45.971: E/AndroidRuntime(444): android.view.WindowManager$BadTokenException: Unable to add window -- token null is not for an application
02-25 17:00:45.971: E/AndroidRuntime(444):  at android.view.ViewRoot.setView(ViewRoot.java:531)
02-25 17:00:45.971: E/AndroidRuntime(444):  at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:177)
02-25 17:00:45.971: E/AndroidRuntime(444):  at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91)
02-25 17:00:45.971: E/AndroidRuntime(444):  at android.app.Dialog.show(Dialog.java:241)
02-25 17:00:45.971: E/AndroidRuntime(444):  at android.app.AlertDialog$Builder.show(AlertDialog.java:802)
02-25 17:00:45.971: E/AndroidRuntime(444):  at com.xxx.myapp.specialclasses.Utility.callAlert(Utility.java:25)
02-25 17:00:45.971: E/AndroidRuntime(444):  at com.xxx.myapp.activities.Activity1.onKeyDown(Activity1.java:149)
02-25 17:00:45.971: E/AndroidRuntime(444):  at android.view.KeyEvent.dispatch(KeyEvent.java:1256)
02-25 17:00:45.971: E/AndroidRuntime(444):  at android.app.Activity.dispatchKeyEvent(Activity.java:2078)
02-25 17:00:45.971: E/AndroidRuntime(444):  at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:1663)
02-25 17:00:45.971: E/AndroidRuntime(444):  at android.view.ViewRoot.deliverKeyEventToViewHierarchy(ViewRoot.java:2560)
02-25 17:00:45.971: E/AndroidRuntime(444):  at android.view.ViewRoot.handleFinishedEvent(ViewRoot.java:2535)
02-25 17:00:45.971: E/AndroidRuntime(444):  at android.view.ViewRoot.handleMessage(ViewRoot.java:1867)
02-25 17:00:45.971: E/AndroidRuntime(444):  at android.os.Handler.dispatchMessage(Handler.java:99)
02-25 17:00:45.971: E/AndroidRuntime(444):  at android.os.Looper.loop(Looper.java:123)
02-25 17:00:45.971: E/AndroidRuntime(444):  at android.app.ActivityThread.main(ActivityThread.java:3683)
02-25 17:00:45.971: E/AndroidRuntime(444):  at java.lang.reflect.Method.invokeNative(Native Method)
02-25 17:00:45.971: E/AndroidRuntime(444):  at java.lang.reflect.Method.invoke(Method.java:507)
02-25 17:00:45.971: E/AndroidRuntime(444):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
02-25 17:00:45.971: E/AndroidRuntime(444):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
02-25 17:00:45.971: E/AndroidRuntime(444):  at dalvik.system.NativeStart.main(Native Method)
02-25 17:05:46.061: I/Process(444): Sending signal. PID: 444 SIG: 9

Answer 1

代替:

Utility.callAlert(message, getApplicationContext());

使用:

Utility.callAlert(message, Activity1.this);

和

public void onClick(DialogInterface dialog, int which) {
                ((Activity)context).finish();
}