안드로이드 Viewpager 안에 RecyclerView 있을때 Appbar 스크롤 버벅임 현상

안드로이드 Viewpager 안에 RecyclerView  있을때 AppBar의 움직임이 버벅거리면서

스크롤이 제대로 안될때가 있다 그럴때는 

아래의 클래스를 추가한뒤 

public class FixAppBarLayoutBehavior extends AppBarLayout.Behavior {

  private static final String TAG = "AppBarLayoutBehavior";

  public FixAppBarLayoutBehavior() {
    super();
  }

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

  // --------------begin added by shaopx -------------

  @Override
  public boolean onInterceptTouchEvent(CoordinatorLayout parent, AppBarLayout child, MotionEvent ev) {
    if (ev.getAction() == MotionEvent.ACTION_DOWN) {
      Object scroller = getSuperSuperField(this, "mScroller");
      if (scroller != null && scroller instanceof OverScroller) {
        OverScroller overScroller = (OverScroller) scroller;
        overScroller.abortAnimation();
      }
    }

    return super.onInterceptTouchEvent(parent, child, ev);
  }

  private Object getSuperSuperField(Object paramClass, String paramString) {
    Field field = null;
    Object object = null;
    try {
      field = paramClass.getClass().getSuperclass().getSuperclass().getDeclaredField(paramString);
      field.setAccessible(true);
      object = field.get(paramClass);
    } catch (Exception e) {
      e.printStackTrace();
    }
    return object;
  }
  // --------------------------- end

  @Override
  public void onNestedScroll(CoordinatorLayout coordinatorLayout, AppBarLayout child, View target,
                             int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed, int type) {
    super.onNestedScroll(coordinatorLayout, child, target, dxConsumed, dyConsumed,
            dxUnconsumed, dyUnconsumed, type);
    stopNestedScrollIfNeeded(dyUnconsumed, child, target, type);
  }

  @Override
  public void onNestedPreScroll(CoordinatorLayout coordinatorLayout, AppBarLayout child,
                                View target, int dx, int dy, int[] consumed, int type) {
    super.onNestedPreScroll(coordinatorLayout, child, target, dx, dy, consumed, type);
    stopNestedScrollIfNeeded(dy, child, target, type);
  }

  private void stopNestedScrollIfNeeded(int dy, AppBarLayout child, View target, int type) {
    if (type == ViewCompat.TYPE_NON_TOUCH) {
      final int currOffset = getTopAndBottomOffset();
      if ((dy < 0 && currOffset == 0)
              || (dy > 0 && currOffset == -child.getTotalScrollRange())) {
        ViewCompat.stopNestedScroll(target, ViewCompat.TYPE_NON_TOUCH);
      }
    }
  }
}

<android.support.design.widget.AppBarLayout
    android:id="@+id/appbar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:stateListAnimator="@null"
    app:layout_behavior="패키지명.FixAppBarLayoutBehavior">

을 추가해서 사용하면 버벅거리는 현상이 사라진다. 

출처 : https://github.com/shaopx/CoordinatorLayoutExample/blob/master/app/src/main/java/com/spx/coordinatorlayoutexample/util/FixAppBarLayoutBehavior.java