触摸屏时停止媒体播放器

时间：2014-09-01 12:24:12

标签： android touch media-player

我正在开发一个应用程序，它包含一个实现ViewPager和3个片段的MainActivity。我在MainActivity中定义了所有逻辑方法，片段只是实现了UI引用的方法。

因此，在MainActivity中，我有一种方法可以解决问题，并以这种方式启动MediaPlayer：

mp = MediaPlayer.create(MainActivity.this, R.raw.alarm);
try {
    mp.setLooping(true);
} catch (IllegalStateException e) {
    e.printStackTrace();
}
mp.start();

这会将声音播放到循环中。现在，我需要能够阻止它只是触摸屏幕，因为我已经通过这种方式实现了onTouchEvent（）方法：

@Override
public boolean onTouchEvent (MotionEvent event) {
    if (event.getAction() == MotionEvent.ACTION_DOWN) {
        /*If sound is playing, stops*/
        if (mp.isPlaying()) {
            mp.stop();
        }
        return true;
    }
    return super.onTouchEvent(event);
}

这就是问题所在。我无法停止声音，所以我认为上面的方法不起作用。一个SO成员让我使用dispatchTouchEvent()而不是onTouchEvent()，但这样做就可以关闭app力而不会在LogCat中抛出任何错误消息。

@Override
public boolean dispatchTouchEvent (MotionEvent event) {
    if (event.getAction() == MotionEvent.ACTION_DOWN) {
        /*If sound is playing, stops*/
        if (mp.isPlaying()) {
            mp.stop();
        }
        return true;
    }
    return super.dispatchTouchEvent(event);
}

所以我不知道该方法有什么问题。或者问题可能是这必须在每个片段而不是在MainAcitivity中实现？

更新

我遇到了eclipse的问题，它显示了logCat信息，但现在已经解决了，这就是它抛出的内容：

09-01 16:43:15.591: E/InputEventReceiver(30873): Exception dispatching input event.
09-01 16:43:15.591: E/MessageQueue-JNI(30873): Exception in MessageQueue callback: handleReceiveCallback
09-01 16:43:15.591: E/MessageQueue-JNI(30873): java.lang.NullPointerException
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at com.itest.MainActivity.dispatchTouchEvent(MainActivity.java:818)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at android.support.v7.app.ActionBarActivityDelegateICS$WindowCallbackWrapper.dispatchTouchEvent(ActionBarActivityDelegateICS.java:260)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:2228)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at android.view.View.dispatchPointerEvent(View.java:8315)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at android.view.ViewRootImpl$ViewPostImeInputStage.processPointerEvent(ViewRootImpl.java:4596)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:4464)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4022)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4076)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4045)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:4156)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:4053)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:4213)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4022)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4076)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4045)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:4053)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4022)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:6403)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:6307)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:6278)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:6243)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:6483)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:185)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at android.os.MessageQueue.nativePollOnce(Native Method)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at android.os.MessageQueue.next(MessageQueue.java:138)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at android.os.Looper.loop(Looper.java:123)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at android.app.ActivityThread.main(ActivityThread.java:5356)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at java.lang.reflect.Method.invokeNative(Native Method)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at java.lang.reflect.Method.invoke(Method.java:515)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
09-01 16:43:15.591: E/MessageQueue-JNI(30873):  at dalvik.system.NativeStart.main(Native Method)
09-01 16:43:15.591: D/AndroidRuntime(30873): Shutting down VM
09-01 16:43:15.601: W/dalvikvm(30873): threadid=1: thread exiting with uncaught exception (group=0x4180bda0)
09-01 16:43:15.601: E/AndroidRuntime(30873): FATAL EXCEPTION: main
09-01 16:43:15.601: E/AndroidRuntime(30873): Process: com.itest, PID: 30873
09-01 16:43:15.601: E/AndroidRuntime(30873): java.lang.NullPointerException
09-01 16:43:15.601: E/AndroidRuntime(30873):    at com.itest.MainActivity.dispatchTouchEvent(MainActivity.java:818)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at android.support.v7.app.ActionBarActivityDelegateICS$WindowCallbackWrapper.dispatchTouchEvent(ActionBarActivityDelegateICS.java:260)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:2228)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at android.view.View.dispatchPointerEvent(View.java:8315)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at android.view.ViewRootImpl$ViewPostImeInputStage.processPointerEvent(ViewRootImpl.java:4596)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:4464)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4022)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4076)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4045)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:4156)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:4053)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:4213)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4022)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4076)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4045)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:4053)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4022)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:6403)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:6307)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:6278)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:6243)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:6483)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:185)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at android.os.MessageQueue.nativePollOnce(Native Method)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at android.os.MessageQueue.next(MessageQueue.java:138)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at android.os.Looper.loop(Looper.java:123)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at android.app.ActivityThread.main(ActivityThread.java:5356)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at java.lang.reflect.Method.invokeNative(Native Method)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at java.lang.reflect.Method.invoke(Method.java:515)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
09-01 16:43:15.601: E/AndroidRuntime(30873):    at dalvik.system.NativeStart.main(Native Method)

MainActivity中的第818行指的是onTouchEvent（）或dispatchTouchEvent（）方法，正好是这一行：

if (mp.isPlaying()) {

1 个答案:

答案 0 :(得分：1)

您正在线上<{1}} 

NullPointerException
最初触摸屏幕时，

if (mp.isPlaying()) { 必须为空。

添加：

mp

希望这有帮助。

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