sample for VelocityTracker

VelocityView.java

public class VelocityView extends View {

    public static final String TAG = "VelocityView";

    private VelocityTracker mVelocityTracker;

    public VelocityView(Context context) {
        super(context);
    }

    public VelocityView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        obtainVelocityTracker(event);
        switch (event.getAction()) {
            case MotionEvent.ACTION_UP:
                final VelocityTracker velocityTracker = mVelocityTracker;
                velocityTracker.computeCurrentVelocity(1000);
                float xVelocity = mVelocityTracker.getXVelocity();
                float yVelocity = mVelocityTracker.getYVelocity();
                Log.i(TAG, "xVelocity: " + xVelocity + ", yVelocity: " + yVelocity);
                mVelocityTracker.clear();
                break;
            default:
                break;
        }
        return true;
    }

    private void obtainVelocityTracker(MotionEvent event) {
        if (mVelocityTracker == null) {
            mVelocityTracker = VelocityTracker.obtain();
        }
        mVelocityTracker.addMovement(event);
    }

    private void releaseVelocityTracker() {
        if (mVelocityTracker != null) {
            mVelocityTracker.recycle();
            mVelocityTracker = null;
        }
    }

    @Override
    protected void onDetachedFromWindow() {
        super.onDetachedFromWindow();
        releaseVelocityTracker();
    }
}