为什么 onTouch() 返回 false 时会产生致命异常？
我编写了一个简单的 MotionEvent 练习，其中我所做的就是记录事件的参数。我通过在主活动中实现 OnTouchListener 并覆盖 onTouch() 来实现这一点。
对于一个按钮，我在 onTouch() 末尾返回 true。那里没有问题。
对于另一个按钮，我在 onTouch() 末尾返回 false。这就是有趣的地方。仅仅返回“false”，就会抛出一个致命异常，并带有一个我不太理解的微小提示：“回收两次！”。
这意味着什么？
更新：根据下面评论中的建议，我添加了 LogCat 异常的详细信息：
03-08 10:35:14.275: ERROR/AndroidRuntime(521): FATAL EXCEPTION: main
03-08 10:35:14.275: ERROR/AndroidRuntime(521): java.lang.RuntimeException: MotionEvent{405215b0 action=0 x=66.0 y=78.0 pressure=1.0 size=0.0} recycled twice!
03-08 10:35:14.275: ERROR/AndroidRuntime(521): at android.view.MotionEvent.recycle(MotionEvent.java:659)
03-08 10:35:14.275: ERROR/AndroidRuntime(521): at android.view.ViewRoot.handleMessage(ViewRoot.java:1880)
03-08 10:35:14.275: ERROR/AndroidRuntime(521): at android.os.Handler.dispatchMessage(Handler.java:99)
03-08 10:35:14.275: ERROR/AndroidRuntime(521): at android.os.Looper.loop(Looper.java:123)
03-08 10:35:14.275: ERROR/AndroidRuntime(521): at android.app.ActivityThread.main(ActivityThread.java:3647)
03-08 10:35:14.275: ERROR/AndroidRuntime(521): at java.lang.reflect.Method.invokeNative(Native Method)
03-08 10:35:14.275: ERROR/AndroidRuntime(521): at java.lang.reflect.Method.invoke(Method.java:507)
03-08 10:35:14.275: ERROR/AndroidRuntime(521): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
03-08 10:35:14.275: ERROR/AndroidRuntime(521): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
03-08 10:35:14.275: ERROR/AndroidRuntime(521): at dalvik.system.NativeStart.main(Native Method)
I wrote a simple MotionEvent exercise in which all I do is log the parameters of the event. I do that by implementing OnTouchListener and overriding onTouch() in the main activity.
For one button, I return true at the end of onTouch(). No problems there.
For another button, I return false at the end of onTouch(). This is where it gets interesting. By mere returning 'false', a FATAL EXCEPTION is thrown with a tiny hint which I don't really understand: "recycled twice!".
What does this mean?
Update: per the suggestion in the comment below, I am adding the details of the exception from LogCat:
03-08 10:35:14.275: ERROR/AndroidRuntime(521): FATAL EXCEPTION: main
03-08 10:35:14.275: ERROR/AndroidRuntime(521): java.lang.RuntimeException: MotionEvent{405215b0 action=0 x=66.0 y=78.0 pressure=1.0 size=0.0} recycled twice!
03-08 10:35:14.275: ERROR/AndroidRuntime(521): at android.view.MotionEvent.recycle(MotionEvent.java:659)
03-08 10:35:14.275: ERROR/AndroidRuntime(521): at android.view.ViewRoot.handleMessage(ViewRoot.java:1880)
03-08 10:35:14.275: ERROR/AndroidRuntime(521): at android.os.Handler.dispatchMessage(Handler.java:99)
03-08 10:35:14.275: ERROR/AndroidRuntime(521): at android.os.Looper.loop(Looper.java:123)
03-08 10:35:14.275: ERROR/AndroidRuntime(521): at android.app.ActivityThread.main(ActivityThread.java:3647)
03-08 10:35:14.275: ERROR/AndroidRuntime(521): at java.lang.reflect.Method.invokeNative(Native Method)
03-08 10:35:14.275: ERROR/AndroidRuntime(521): at java.lang.reflect.Method.invoke(Method.java:507)
03-08 10:35:14.275: ERROR/AndroidRuntime(521): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
03-08 10:35:14.275: ERROR/AndroidRuntime(521): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
03-08 10:35:14.275: ERROR/AndroidRuntime(521): at dalvik.system.NativeStart.main(Native Method)
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您是否在回收然后传递
false？如果您返回 false，框架将假定 MotionEvent 仍然有效，并将对其进行自己的处理。
来自文档：
Are you recycling and then passing
false?The framework will assume that the MotionEvent is still valid if you return false and will do its own processing with it.
From the docs: