Android Activity has leaked window that was originally added

今天调试程序时log中突然打印这样的错误，但是程序并没有crash，为了不放过一个错误，我决定调查一下。

当时是离开一个activity，然后提示是否退出此界面，接下来就打印此错误：

03-08 18:02:48.521: E/WindowManager(6340): Activity com.linc.megatron.activity.ExamActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@40568ea8 that was originally added here
03-08 18:02:48.521: E/WindowManager(6340): android.view.WindowLeaked: Activity com.linc.megatron.activity.ExamActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@40568ea8 that was originally added here
03-08 18:02:48.521: E/WindowManager(6340):     at android.view.ViewRoot.<init>(ViewRoot.java:264)
03-08 18:02:48.521: E/WindowManager(6340):     at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:148)
03-08 18:02:48.521: E/WindowManager(6340):     at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91)
03-08 18:02:48.521: E/WindowManager(6340):     at android.view.Window$LocalWindowManager.addView(Window.java:424)
03-08 18:02:48.521: E/WindowManager(6340):     at android.app.Dialog.show(Dialog.java:241)
03-08 18:02:48.521: E/WindowManager(6340):     at com.linc.megatron.base.BackKeyActivity.showDialog(BackKeyActivity.java:76)
03-08 18:02:48.521: E/WindowManager(6340):     at com.linc.megatron.base.BackKeyActivity.onKeyDown(BackKeyActivity.java:62)
03-08 18:02:48.521: E/WindowManager(6340):     at android.view.KeyEvent.dispatch(KeyEvent.java:1256)
03-08 18:02:48.521: E/WindowManager(6340):     at android.app.Activity.dispatchKeyEvent(Activity.java:2078)
03-08 18:02:48.521: E/WindowManager(6340):     at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:1709)
03-08 18:02:48.521: E/WindowManager(6340):     at android.view.ViewRoot.deliverKeyEventToViewHierarchy(ViewRoot.java:2628)
03-08 18:02:48.521: E/WindowManager(6340):     at android.view.ViewRoot.handleFinishedEvent(ViewRoot.java:2603)
03-08 18:02:48.521: E/WindowManager(6340):     at android.view.ViewRoot.handleMessage(ViewRoot.java:1875)
03-08 18:02:48.521: E/WindowManager(6340):     at android.os.Handler.dispatchMessage(Handler.java:99)
03-08 18:02:48.521: E/WindowManager(6340):     at android.os.Looper.loop(Looper.java:123)
03-08 18:02:48.521: E/WindowManager(6340):     at android.app.ActivityThread.main(ActivityThread.java:3687)
03-08 18:02:48.521: E/WindowManager(6340):     at java.lang.reflect.Method.invokeNative(Native Method)
03-08 18:02:48.521: E/WindowManager(6340):     at java.lang.reflect.Method.invoke(Method.java:507)
03-08 18:02:48.521: E/WindowManager(6340):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
03-08 18:02:48.521: E/WindowManager(6340):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625)
03-08 18:02:48.521: E/WindowManager(6340):     at dalvik.system.NativeStart.main(Native Method)

显然，我用Dialog确认是否退出，但是activity销毁后并没有处理Dialog的退出。 

解决办法：

知道了问题所在就容易解决问题了。只需要在activity销毁时关闭Dialog就好。

    @Override
    protected void onDestroy() {
        if(mDialog != null) {
            mDialog.dismiss();
        }
        super.onDestroy();
    }