Android 使用onFling手势时出现NullPointerException

我在onFling方法中捕获了NullPointerException。。。 这种情况并不总是发生

    class MyGestureDetector extends SimpleOnGestureListener 
    {
        @Override
        public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) 
        {


            try
            {
                if(e1.getX() > e2.getX() && (e1.getX() - e2.getX()) > SWIPE_MIN_DISTANCE ) 
                {
        Log.i("Fling Gesture ","Going Right...Dec");
        Intent i = new Intent(nov.this, dec.class);
        startActivity(i);
        finish();
                }
    else if (e1.getX() < e2.getX() && (e2.getX() - e1.getX()) > SWIPE_MIN_DISTANCE ) 
                {
    Log.i("Fling Gesture ","Going Left...OCT");

    Intent i = new Intent(nov.this, oct.class);
                    i.setFlags(Intent.FLAG_ACTIVITY_NO_ANIMATION);
                    overridePendingTransition(android.R.anim.slide_out_right,android.R.anim.slide_in_left);

                    startActivity(i);
                    finish();
                }

            } catch (Exception e) 
            {
            }
            return true;
        }

只有在向右移动时才会发生异常。。。 请告诉我我哪里错了？？？？。。。。

---

谢谢…

在onFling开始时进行空检查…在使用所有接收到的对象值之前

我有同样的问题。。。解决过吗？我有一个水平滚动视图和另一个垂直滚动的滚动视图。。。在everywhere fling上效果很好，但在垂直滚动视图上。@yahya它并没有解决。。。但我只通过检查velocityX就绕过了它。如果是-ve，则fling是从右到左的，而+ve是从左到右的。e、 g.ifvelocityX<-300谢谢@ShashankDegloorkar您的解决方案也适用于我：+1

09-07 10:44:09.584: WARN/System.err(8721): java.lang.NullPointerException
09-07 10:44:09.584: WARN/System.err(8721):     at com.MarKal11.KAL$MyGestureDetector.onFling(KAL.java:70)
09-07 10:44:09.594: WARN/System.err(8721):     at android.view.GestureDetector.onTouchEvent(GestureDetector.java:568)
09-07 10:44:09.594: WARN/System.err(8721):     at com.MarKal11.KAL$1.onTouch(KAL.java:114)
09-07 10:44:09.594: WARN/System.err(8721):     at android.view.View.dispatchTouchEvent(View.java:3928)
09-07 10:44:09.594: WARN/System.err(8721):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:955)
09-07 10:44:09.594: WARN/System.err(8721):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1015)
09-07 10:44:09.594: WARN/System.err(8721):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1015)
09-07 10:44:09.594: WARN/System.err(8721):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1015)
09-07 10:44:09.604: WARN/System.err(8721):     at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1772)
09-07 10:44:09.604: WARN/System.err(8721):     at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1145)
09-07 10:44:09.604: WARN/System.err(8721):     at android.app.Activity.dispatchTouchEvent(Activity.java:2214)
09-07 10:44:09.604: WARN/System.err(8721):     at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1747)
09-07 10:44:09.604: WARN/System.err(8721):     at android.view.ViewRoot.deliverPointerEvent(ViewRoot.java:2336)
09-07 10:44:09.604: WARN/System.err(8721):     at android.view.ViewRoot.handleMessage(ViewRoot.java:1976)
09-07 10:44:09.614: WARN/System.err(8721):     at android.os.Handler.dispatchMessage(Handler.java:99)
09-07 10:44:09.614: WARN/System.err(8721):     at android.os.Looper.loop(Looper.java:143)
09-07 10:44:09.614: WARN/System.err(8721):     at android.app.ActivityThread.main(ActivityThread.java:4277)
09-07 10:44:09.614: WARN/System.err(8721):     at java.lang.reflect.Method.invokeNative(Native Method)
09-07 10:44:09.614: WARN/System.err(8721):     at java.lang.reflect.Method.invoke(Method.java:507)
09-07 10:44:09.614: WARN/System.err(8721):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
09-07 10:44:09.614: WARN/System.err(8721):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
09-07 10:44:09.624: WARN/System.err(8721):     at dalvik.system.NativeStart.main(Native Method)