旋转后以及关闭应用程序并再次打开后无法恢复RecyclerView的滚动posiotn。在第一种情况下,我可以在Manifest中使用android:configChanges
,但在重新打开应用程序后它无效。
这是我的代码。尝试恢复状态后,我看到一个没有列表的空屏幕。
public class MainActivity extends AppCompatActivity implements IMainContract.View {
private final String BUNDLE_RECYCLER_LAYOUT = MainActivity.class.getSimpleName() + ".save.state.list";
private IMainContract.Presenter mainPresenter;
private MainAdapter adapter;
private LinearLayoutManager layoutManager;
private ImageView ivRefresh;
private ProgressBar progressBar;
private RecyclerView rvUsers;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ivRefresh = (ImageView) findViewById(R.id.ivRefresh);
progressBar = (ProgressBar) findViewById(R.id.progressBar);
rvUsers = (RecyclerView) findViewById(R.id.rvUsers);
layoutManager = new LinearLayoutManager(this);
rvUsers.setLayoutManager(layoutManager);
mainPresenter = new MainPresenter(Repository.getInstance(this), this);
adapter = new MainAdapter(new ArrayList<>(), this);
rvUsers.setAdapter(adapter);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
ivRefresh.setOnClickListener(v -> mainPresenter.onRefreshPressed());
if (savedInstanceState != null) {
Parcelable savedRecyclerLayoutState = savedInstanceState.getParcelable(BUNDLE_RECYCLER_LAYOUT);
layoutManager.onRestoreInstanceState(savedRecyclerLayoutState);
} else {
mainPresenter.subscribe();
}
}
@Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putParcelable(BUNDLE_RECYCLER_LAYOUT, layoutManager.onSaveInstanceState());
}
//...
}
答案 0 :(得分:2)
您需要在stackoverflow上关注此answer。更改您的代码
public class MainActivity extends AppCompatActivity {
private final String KEY_RECYCLER_STATE = "recycler_state";
private MainAdapter adapter;
private LinearLayoutManager layoutManager;
private ImageView ivRefresh;
private ProgressBar progressBar;
private RecyclerView rvUsers;
private static Bundle mBundleRecyclerViewState;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ivRefresh = (ImageView) findViewById(R.id.ivRefresh);
progressBar = (ProgressBar) findViewById(R.id.progressBar);
rvUsers = (RecyclerView) findViewById(R.id.rvUsers);
layoutManager = new LinearLayoutManager(this);
rvUsers.setLayoutManager(layoutManager);
adapter = new MainAdapter(new ArrayList<>(), this);
rvUsers.setAdapter(adapter);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
}
@Override
protected void onPause()
{
super.onPause();
// save RecyclerView state
mBundleRecyclerViewState = new Bundle();
Parcelable listState = rvUsers.getLayoutManager().onSaveInstanceState();
mBundleRecyclerViewState.putParcelable(KEY_RECYCLER_STATE, listState);
}
@Override
protected void onResume()
{
super.onResume();
// restore RecyclerView state
if (mBundleRecyclerViewState != null) {
Parcelable listState = mBundleRecyclerViewState.getParcelable(KEY_RECYCLER_STATE);
rvUsers.getLayoutManager().onRestoreInstanceState(listState);
}
}
}
答案 1 :(得分:1)
您需要覆盖onRestoreInstanceState()
并使用已保存的recyclerView.getLayoutManager()
bundle
Parcelable savedRecyclerLayoutState ;
@Override
public void onRestoreInstanceState(@Nullable Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
if(savedInstanceState != null)
{
savedRecyclerLayoutState = savedInstanceState.getParcelable(BUNDLE_RECYCLER_LAYOUT);
rvUsers.getLayoutManager().onRestoreInstanceState(savedRecyclerLayoutState);
}
}
您还需要覆盖活动中的onResume()
@Override
protected void onResume() {
super.onResume();
if (savedRecyclerLayoutState != null) {
layoutManager.onRestoreInstanceState(savedRecyclerLayoutState );
}
}
答案 2 :(得分:0)
最初,您必须通过调用以下方式获取RecyclerView的当前滚动位置:
int index = rvUsers.getFirstVisiblePosition();
然后您必须在方向更改时保存此值,并且再次创建RecyclerView时,您必须将RecyclerView移动到此索引。
我认为这可行:
rvUsers.smoothScrollToPosition(int index)
如果您使用的是旧版本 使用
setSelection(int position)
和
getFirstVisiblePosition()
方法
答案 3 :(得分:0)
您可以在共享首选项中存储位置,当您重新启动应用程序时,从首选项中获取值并相应地填充回收站视图
答案 4 :(得分:0)
使用已填充的数据设置适配器很重要。在这种情况下,位置会自动恢复。