GestureDetector-onfling不执行

今天在做计算器的时候，遇到了一个问题，就是当我使用GestureDetector的时候，onFling方法不执行，而其他的可以执行。代码如下

 @Override
    public boolean onDown(MotionEvent arg0) {
        android.util.Log.e("zhangshuli", "getx(down)===="+arg0.getX()+"getY(down)===="+arg0.getY());
        myGestureSign = false;
        return false;
    } 

 @Override
    public boolean onFling(MotionEvent arg0, MotionEvent arg1, float arg2, float arg3) {
/* Vanzo:zhangshuli on: Tue, 24 Mar 2015 20:52:05 +0000
 * modify for v5 calculator
        if (myGestureSign) {
            return true;
        }
        if (Math.abs(arg0.getX() - arg1.getX()) > 120.0F) {
            myGestureSign = true;
            if (!mDrawerLayout.isDrawerVisible(GravityCompat.END)) {
                mDrawerLayout.openDrawer(GravityCompat.END);
            }
        } else if (arg1.getX() - arg0.getX() > 120.0F) {
            if (mDrawerLayout.isDrawerVisible(GravityCompat.END)) {
                mDrawerLayout.closeDrawer(GravityCompat.END);
            }
        }
        android.util.Log.e("zhangshuli", "arg0.getx(fling)===="+arg0.getX()+"getY(fling)===="+arg0.getY()+"arg1.getx(fling)===="+arg1.getX()+"arg1.getY(fling)===="+arg1.getY());
 */
// End of Vanzo: zhangshuli
        return false;
    }   

后来在网上找到了原因，只要把onDown()的返回值更改成true就行了

如下

 @Override
    public boolean onDown(MotionEvent arg0) {
        android.util.Log.e("zhangshuli", "getx(down)===="+arg0.getX()+"getY(down)===="+arg0.getY());
        myGestureSign = false;
        return true;
    }