recyclerView下滑到某个position,按钮显示,点击按钮返回recyclerView的顶部;
1.xml布局:
<ImageView
android:id="@+id/iv_batch_top"
android:layout_width="40dp"
android:layout_height="40dp"
android:src="@mipmap/fragment_batch_back" />
2.position>20时,将按钮显示;小于等于则隐藏;
private RecyclerView mFolderRv;
....
GridLayoutManager llm = new GridLayoutManager(getMainActivity(), 1);
llm.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
@Override
public int getSpanSize(int i) {
if (i <= 20) {
mBackTopIv.setVisibility(View.GONE);
} else {
mBackTopIv.setVisibility(View.VISIBLE);
}
return 1;//返回 1
}
});
mFolderRv.setLayoutManager(llm);
3.按钮的点击事件:
....
case R.id.iv_import_top:
mFolderRv.scrollToPosition(0);//返回到顶部 即position=0;
break;
...