我正在尝试在我的应用中实现多点触控功能但是只要我触摸屏幕就会崩溃。如果我使用单个触摸事件而不是mutitouch
，相同的应用程序运行正常这是onTouchEvent实现的单次触摸
@Override
public boolean onTouchEvent(MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_DOWN) {
pointer1 = event.getPointerId(0);
_x = event.getX(event.findPointerIndex(pointer1));
_y = event.getY(event.findPointerIndex(pointer1));
}
if (event.getAction() == MotionEvent.ACTION_POINTER_DOWN){
pointer2 = event.getPointerId(1);
_x = event.getX(event.findPointerIndex(pointer2));
_y = event.getY(event.findPointerIndex(pointer2));
}
if (event.getAction() == MotionEvent.ACTION_MOVE) {
final float xdiff = (_x - event.getX(event.findPointerIndex(event.getPointerId(0))));
final float ydiff = (_y - event.getY(event.findPointerIndex(event.getPointerId(0))));
myThread.getGameState().surfaceTouched(_x, _y);
_x = event.getX(event.findPointerIndex(event.getPointerId(0)));
_y = event.getY(event.findPointerIndex(event.getPointerId(0)));
}
return true;
}
以下是Multi-Touch onTouchEvent代码（一直给我提问的）
@Override
public boolean onTouchEvent(MotionEvent event) {
int pointerIndex = event.getActionIndex(); //Getting Pointer Index
int pointerId = event.getPointerId(pointerIndex); //Getting Pointer ID
int maskedAction = event.getActionMasked(); //Getting masked (not pointer specefic) action
if ((event.getAction() == MotionEvent.ACTION_DOWN) || (event.getAction() == MotionEvent.ACTION_POINTER_DOWN)) {
PointF f = new PointF();
f.x = event.getX(pointerIndex);
f.y = event.getY(pointerIndex);
mActivePointers.put(pointerId, f);
} else if (event.getAction() == MotionEvent.ACTION_MOVE) { // a pointer was moved
for (int size = event.getPointerCount(), i = 0; i < size; i++) {
PointF point = mActivePointers.get(event.getPointerId(i));
myThread.getGameState().surfaceTouched(point.x, point.y);
if (point != null) {
point.x = event.getX(i);
point.y = event.getY(i);
}
}
}
return true;
}
这是Logcat输出
10-18 22:08:05.218 5216-5253/com.nblsoft.pong I/OpenGLRenderer﹕ Initialized EGL, version 1.4
10-18 22:08:07.752 5216-5216/com.nblsoft.pong E/InputEventReceiver﹕ Exception dispatching input event.
10-18 22:08:07.753 5216-5216/com.nblsoft.pong E/MessageQueue-JNI﹕ Exception in MessageQueue callback: handleReceiveCallback
10-18 22:08:07.755 5216-5216/com.nblsoft.pong E/MessageQueue-JNI﹕ java.lang.NullPointerException: Attempt to invoke virtual method 'void android.util.SparseArray.put(int, java.lang.Object)' on a null object reference
at com.nblsoft.pong.GameView.onTouchEvent(GameView.java:147)
at android.view.View.dispatchTouchEvent(View.java:9294)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2553)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2197)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2553)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2197)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2553)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2197)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2553)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2197)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2553)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2197)
at com.android.internal.policy.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:2403)
at com.android.internal.policy.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1737)
at android.app.Activity.dispatchTouchEvent(Activity.java:2765)
at android.support.v7.internal.view.WindowCallbackWrapper.dispatchTouchEvent(WindowCallbackWrapper.java:59)
at com.android.internal.policy.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:2364)
at android.view.View.dispatchPointerEvent(View.java:9514)
at android.view.ViewRootImpl$ViewPostImeInputStage.processPointerEvent(ViewRootImpl.java:4230)
at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:4096)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3642)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3695)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3661)
at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3787)
at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3669)
at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:3844)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3642)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3695)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3661)
at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3669)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3642)
at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:5922)
at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:5896)
at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:5857)
at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:6025)
at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:185)
at android.os.MessageQueue.nativePollOnce(Native Method)
at android.os.MessageQueue.next(MessageQueue.java:323)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
10-18 22:08:07.755 5216-5216/com.nblsoft.pong D/AndroidRuntime﹕ Shutting down VM
10-18 22:08:07.756 5216-5216/com.nblsoft.pong E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.nblsoft.pong, PID: 5216
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.util.SparseArray.put(int, java.lang.Object)' on a null object reference
at com.nblsoft.pong.GameView.onTouchEvent(GameView.java:147)
at android.view.View.dispatchTouchEvent(View.java:9294)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2553)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2197)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2553)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2197)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2553)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2197)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2553)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2197)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2553)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2197)
at com.android.internal.policy.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:2403)
at com.android.internal.policy.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1737)
at android.app.Activity.dispatchTouchEvent(Activity.java:2765)
at android.support.v7.internal.view.WindowCallbackWrapper.dispatchTouchEvent(WindowCallbackWrapper.java:59)
at com.android.internal.policy.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:2364)
at android.view.View.dispatchPointerEvent(View.java:9514)
at android.view.ViewRootImpl$ViewPostImeInputStage.processPointerEvent(ViewRootImpl.java:4230)
at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:4096)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3642)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3695)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3661)
at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3787)
at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3669)
at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:3844)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3642)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3695)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3661)
at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3669)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3642)
at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:5922)
at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:5896)
at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:5857)
at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:6025)
at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:185)
at android.os.MessageQueue.nativePollOnce(Native Method)
at android.os.MessageQueue.next(MessageQueue.java:323)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)