Android 判断一个视图是否滚动到顶部

Android 应用开发中有时候需要自定义滚动，或者判断一个view是否滚动到顶部

public boolean canChildScrollUp(View mTarget) {       if (android.os.Build.VERSION.SDK_INT < 14) {        if (mTarget instanceof AbsListView) {            final AbsListView absListView = (AbsListView) mTarget;            return absListView.getChildCount() > 0                    && (absListView.getFirstVisiblePosition() > 0 || absListView.getChildAt(0)                    .getTop() < absListView.getPaddingTop());        } else {            return ViewCompat.canScrollVertically(mTarget, -1) || mTarget.getScrollY() > 0;        }    } else {        return ViewCompat.canScrollVertically(mTarget, -1);    }}