LayoutManager.onSaveInstanceState() 不起作用，怎么回事？

程序员新人

我想GridLayoutManager 保存我的RecyclerView的状态，但是当调用 onSaveInstanceState() 的时总是返回同一个对象.我用方法"findFirstVisibleItemPosition"时，它总是返回 -1.

RecyclerView 有适配器，适配器有一些元素，我可以滚动它们！我不知道为什么无法获得完全初始化和工作组件的项目位置！请帮忙！

这是我的代码:

@Override
protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);

    outState.putParcelable(BUNDLE_MOVIES_RECYCLER_VIEW_STATE, mMoviesRecyclerView.getLayoutManager().onSaveInstanceState());

    outState.putInt(BUNDLE_SEGMENT_POSITION, mSelectedFilterPosition);
    outState.putSerializable(BUNDLE_NOW_PLAYING_MOVIE, mNowPlayingMovie);
    outState.putSerializable(BUNDLE_SEGMENTED_MOVIES, mSegmentMovies);
}
解决方案参考了这个帖子：https://www.itbaoku.cn/post/2469247/LayoutManager-onSaveInstanceState()-not-working
解决方案

问题已解决！为了保存布局管理器的状态，需要在活动的 onPause 方法中调用 LayoutManager.onSaveInstanceState() 方法.因为在活动 LayoutManager 的 onSaveInstanceState 中已经将其从视图中清除，或者只是删除布局配置.代码示例:

public class MainActivity extends AppCompatActivity { RecyclerView recyclerView; private Parcelable mLayoutManagerState; private static final String LAYOUT_MANAGER_STATE = "LAYOUT_MANAGER_STATE"; @Override protected void onPause() {    super.onPause();    mLayoutManagerState = recyclerView.getLayoutManager().onSaveInstanceState(); } @Override public void onCreate(Bundle savedInstanceState, PersistableBundle persistentState) {    super.onCreate(savedInstanceState, persistentState);    recyclerView = (RecyclerView) findViewById(R.id.recyclerview);    if (savedInstanceState != null) {        mLayoutManagerState = savedInstanceState.getParcelable(LAYOUT_MANAGER_STATE);        recyclerView.getLayoutManager().onRestoreInstanceState(mLayoutManagerState);    } }  @Override public void onSaveInstanceState(Bundle outState, PersistableBundle outPersistentState) {    super.onSaveInstanceState(outState, outPersistentState);    outState.putParcelable(LAYOUT_MANAGER_STATE, mLayoutManagerState); }}