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：

- ::48.521: E/WindowManager(): Activity com.linc.megatron.activity.ExamActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@40568ea8 that was originally added here
- ::48.521: E/WindowManager(): android.view.WindowLeaked: Activity com.linc.megatron.activity.ExamActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@40568ea8 that was originally added here
- ::48.521: E/WindowManager():     at android.view.ViewRoot.<init>(ViewRoot.java:)
- ::48.521: E/WindowManager():     at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:)
- ::48.521: E/WindowManager():     at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:)
- ::48.521: E/WindowManager():     at android.view.Window$LocalWindowManager.addView(Window.java:)
- ::48.521: E/WindowManager():     at android.app.Dialog.show(Dialog.java:)
- ::48.521: E/WindowManager():     at com.linc.megatron.base.BackKeyActivity.showDialog(BackKeyActivity.java:)
- ::48.521: E/WindowManager():     at com.linc.megatron.base.BackKeyActivity.onKeyDown(BackKeyActivity.java:)
- ::48.521: E/WindowManager():     at android.view.KeyEvent.dispatch(KeyEvent.java:)
- ::48.521: E/WindowManager():     at android.app.Activity.dispatchKeyEvent(Activity.java:)
- ::48.521: E/WindowManager():     at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:)
- ::48.521: E/WindowManager():     at android.view.ViewRoot.deliverKeyEventToViewHierarchy(ViewRoot.java:)
- ::48.521: E/WindowManager():     at android.view.ViewRoot.handleFinishedEvent(ViewRoot.java:)
- ::48.521: E/WindowManager():     at android.view.ViewRoot.handleMessage(ViewRoot.java:)
- ::48.521: E/WindowManager():     at android.os.Handler.dispatchMessage(Handler.java:)
- ::48.521: E/WindowManager():     at android.os.Looper.loop(Looper.java:)
- ::48.521: E/WindowManager():     at android.app.ActivityThread.main(ActivityThread.java:)
- ::48.521: E/WindowManager():     at java.lang.reflect.Method.invokeNative(Native Method)
- ::48.521: E/WindowManager():     at java.lang.reflect.Method.invoke(Method.java:)
- ::48.521: E/WindowManager():     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:)
- ::48.521: E/WindowManager():     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:)
- ::48.521: E/WindowManager():     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();
    }