看到下面代码中用了AND位运算是为了什么呢？ public boolean onTouchEvent(MotionEvent event) { int action = event.getAction(); switch (action & MotionEvent.ACTION_MASK) { case MotionEvent.ACTION_DOWN: showMsg(“ACTION_DOWN” + action); break; case MotionEvent.ACTION_UP: showMsg(“ACTION_UP” + action); break; case MotionEvent.ACTION_POINTER_UP: …

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