我有一个 TextView,我为它分配了 onTouchListener 和 onClickListener:
myTextView.setOnTouchListener(new OnTouchListener() {
public boolean onTouch(View v, MotionEvent event) {
_gestureDetector.onTouchEvent(event);
return false;
}
});
myTextView.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
// Show Toast Notification
}
});
onTouchListener 将检测手势检测器的 onFling()。除了 Android 4.0(冰淇淋三明治)之外,此代码工作没有任何问题。在 4.0 中,我在“_gestureDetector.onTouchEvent(event);”上收到 NullPointerException (当我尝试投掷时)。
但是,如果我注释掉 onClickListener,则 fling 将起作用,并且我不会收到 NullPointerException。
我假设如果两个触摸监听器都返回 false,则该事件不会被消耗,从而允许两者都工作。
有人有什么想法吗?谢谢!
这是我的更多代码:
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.calendar);
_gestureDetector = new GestureDetector(new GestureListener());
}
private class GestureListener extends SimpleOnGestureListener {
@Override
public boolean onDown(MotionEvent e) {
return false;
}
@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
float velocityY) {
if (e1.getY() - e2.getY() > SWIPE_MIN_DISTANCE
&& Math.abs(velocityY) > SWIPE_THRESHOLD_VELOCITY) {
// Bottom to top
_calendarTableLayout.removeAllViews();
int month = _calendar.get(Calendar.MONTH);
_calendar.set(Calendar.MONTH, month + 1);
_calendar.set(Calendar.DATE, 1); // important
drawCalendar();
return true;
} else if (e2.getY() - e1.getY() > SWIPE_MIN_DISTANCE
&& Math.abs(velocityY) > SWIPE_THRESHOLD_VELOCITY) {
// Top to bottom
_calendarTableLayout.removeAllViews();
int month = _calendar.get(Calendar.MONTH);
_calendar.set(Calendar.MONTH, month - 1);
_calendar.set(Calendar.DATE, 1); // important
redrawCalendar();
return true;
}
return false;
}
@Override
public void onLongPress(MotionEvent e) {
// Do nothing
}
@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2,
float distanceX, float distanceY) {
// Do nothing
return false;
}
@Override
public void onShowPress(MotionEvent e) {
// Do nothing
}
@Override
public boolean onSingleTapUp(MotionEvent e) {
// Do nothing
return false;
}
}
堆栈跟踪:
01-27 11:12:16.406: E/AndroidRuntime(1448): FATAL EXCEPTION: main
01-27 11:12:16.406: E/AndroidRuntime(1448): java.lang.NullPointerException
01-27 11:12:16.406: E/AndroidRuntime(1448): at android.view.GestureDetector.onTouchEvent(GestureDetector.java:587)
01-27 11:12:16.406: E/AndroidRuntime(1448): at com.my.package.MyActivity$9.onTouch(MyActivity.java:287)
01-27 11:12:16.406: E/AndroidRuntime(1448): at android.view.View.dispatchTouchEvent(View.java:5481)
01-27 11:12:16.406: E/AndroidRuntime(1448): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1959)
01-27 11:12:16.406: E/AndroidRuntime(1448): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1728)
01-27 11:12:16.406: E/AndroidRuntime(1448): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1959)
01-27 11:12:16.406: E/AndroidRuntime(1448): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1728)
01-27 11:12:16.406: E/AndroidRuntime(1448): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1959)
01-27 11:12:16.406: E/AndroidRuntime(1448): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1728)
01-27 11:12:16.406: E/AndroidRuntime(1448): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1959)
01-27 11:12:16.406: E/AndroidRuntime(1448): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1728)
01-27 11:12:16.406: E/AndroidRuntime(1448): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1959)
01-27 11:12:16.406: E/AndroidRuntime(1448): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1728)
01-27 11:12:16.406: E/AndroidRuntime(1448): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1959)
01-27 11:12:16.406: E/AndroidRuntime(1448): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1728)
01-27 11:12:16.406: E/AndroidRuntime(1448): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1959)
01-27 11:12:16.406: E/AndroidRuntime(1448): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1728)
01-27 11:12:16.406: E/AndroidRuntime(1448): at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1892)
01-27 11:12:16.406: E/AndroidRuntime(1448): at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1371)
01-27 11:12:16.406: E/AndroidRuntime(1448): at android.app.Activity.dispatchTouchEvent(Activity.java:2364)
01-27 11:12:16.406: E/AndroidRuntime(1448): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java: 1840)
01-27 11:12:16.406: E/AndroidRuntime(1448): at android.view.View.dispatchPointerEvent(View.java:5662)
01-27 11:12:16.406: E/AndroidRuntime(1448): at android.view.ViewRootImpl.deliverPointerEvent(ViewRootImpl.java:2863)
01-27 11:12:16.406: E/AndroidRuntime(1448): at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2442)
01-27 11:12:16.406: E/AndroidRuntime(1448): at android.os.Handler.dispatchMessage(Handler.java:99)
01-27 11:12:16.406: E/AndroidRuntime(1448): at android.os.Looper.loop(Looper.java:137)
01-27 11:12:16.406: E/AndroidRuntime(1448): at android.app.ActivityThread.main(ActivityThread.java:4340)
01-27 11:12:16.406: E/AndroidRuntime(1448): at java.lang.reflect.Method.invokeNative(Native Method)
01-27 11:12:16.406: E/AndroidRuntime(1448): at java.lang.reflect.Method.invoke(Method.java:511)
01-27 11:12:16.406: E/AndroidRuntime(1448): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
01-27 11:12:16.406: E/AndroidRuntime(1448): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
01-27 11:12:16.406: E/AndroidRuntime(1448): at dalvik.system.NativeStart.main(Native Method)