Android RecyclerView没有'；我不记得屏幕旋转时的选择

在我的

RecyclerView

的

Adapter

中，我使用以下方法来记住当前选择的项目并在屏幕上恢复它：

private final static String SELECTED_ITEM = "MyAdapter.selectedItem";

public void onSaveInstanceState(Bundle outState){
    Log.i("onSave","OnSave "+mSelectedItem);
    outState.putInt(SELECTED_ITEM, mSelectedItem);
}

public void onRestoreInstanceState(Bundle savedInstanceState){
    if(savedInstanceState.containsKey(SELECTED_ITEM)){
        Log.i("onRestore","OnRestore " + savedInstanceState.getInt(SELECTED_ITEM));
        notifyItemChanged(mSelectedItem);
        mSelectedItem = savedInstanceState.getInt(SELECTED_ITEM);
        notifyItemChanged(mSelectedItem);
        mRecyclerView.getLayoutManager().scrollToPosition(mSelectedItem);
    }
}

在我的

片段

中，我使用了

回收视图

：

@Override
public void onSaveInstanceState(Bundle outState) {
    if(null != mRecyclerView && null != mRecyclerView.getAdapter()){
        ((MyAdapter)mRecyclerView.getAdapter()).onSaveInstanceState(outState);
    }
    super.onSaveInstanceState(outState);
}

@Override
public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
    if(null!=savedInstanceState){
        if(null != mRecyclerView && null != mRecyclerView.getAdapter()){
            ((MyAdapter)mRecyclerView.getAdapter()).onRestoreInstanceState(savedInstanceState);
        }
    }
}

我看到

日志

消息，但是

适配器

不记得选择

多亏了塞尔文，我很快意识到问题在于每次屏幕旋转时我都在重新创建

片段

，而新的

片段

，当然，没有要恢复的选择int

在根

活动的
onCreate
方法中，检查您是否第一次创建
活动
：

@Override
    protected void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main_layout);
        mContentLayout = (FrameLayout)findViewById(R.id.main_content_frame);
        if(null==savedInstanceState) {
            mFragment = new MyFragment();
            FragmentManager fragmentManager = getSupportFragmentManager();
            FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
            fragmentTransaction.replace(mContentLayout.getId(), mPlatformsFragment);
            fragmentTransaction.commit();
        }
    }

然后在
片段中
，要保存所选项目，请使用：

private final static String SELECTED_ITEM = "MyAdapter.mSelectedItem";

//Save your selection
@Override
public void onSaveInstanceState(Bundle outState) {
    if(null!=mAdapter){
        outState.putInt(SELECTED_ITEM, mAdapter.mSelectedItem);
    }
    super.onSaveInstanceState(outState);
}

//Restore your selection
@Override
public void onActivityCreated(Bundle savedInstanceState){
    super.onActivityCreated(savedInstanceState);
    if (savedInstanceState != null) {
        mAdapter.notifyItemChanged(platformsAdapter.mSelectedItem);
        mAdapter.mSelectedItem = savedInstanceState.getInt(SELECTED_ITEM, 0);
        mAdapter.notifyItemChanged(platformsAdapter.mSelectedItem);
        mRecyclerView.post(new Runnable() {
            @Override
            public void run() {
                //Align selection to top
                mLayoutManager
                    .scrollToPositionWithOffset(mAdapter.mSelectedItem, 0);
            }
        });
    }
}

多亏了塞尔文，我很快意识到问题在于每次屏幕旋转时我都在重新创建
片段
，当然，新的
片段
，没有要恢复的选择int

在根
活动的
onCreate
方法中，检查您是否第一次创建
活动
：

@Override
    protected void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main_layout);
        mContentLayout = (FrameLayout)findViewById(R.id.main_content_frame);
        if(null==savedInstanceState) {
            mFragment = new MyFragment();
            FragmentManager fragmentManager = getSupportFragmentManager();
            FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
            fragmentTransaction.replace(mContentLayout.getId(), mPlatformsFragment);
            fragmentTransaction.commit();
        }
    }

然后在
片段中
，要保存所选项目，请使用：

private final static String SELECTED_ITEM = "MyAdapter.mSelectedItem";

//Save your selection
@Override
public void onSaveInstanceState(Bundle outState) {
    if(null!=mAdapter){
        outState.putInt(SELECTED_ITEM, mAdapter.mSelectedItem);
    }
    super.onSaveInstanceState(outState);
}

//Restore your selection
@Override
public void onActivityCreated(Bundle savedInstanceState){
    super.onActivityCreated(savedInstanceState);
    if (savedInstanceState != null) {
        mAdapter.notifyItemChanged(platformsAdapter.mSelectedItem);
        mAdapter.mSelectedItem = savedInstanceState.getInt(SELECTED_ITEM, 0);
        mAdapter.notifyItemChanged(platformsAdapter.mSelectedItem);
        mRecyclerView.post(new Runnable() {
            @Override
            public void run() {
                //Align selection to top
                mLayoutManager
                    .scrollToPositionWithOffset(mAdapter.mSelectedItem, 0);
            }
        });
    }
}

RecyclerView
有自己的。。。从Fragment的生命周期来看，似乎在所有视图的恢复安装状态之前调用了创建的
onActivityCreated
。@Selvin它不存储关于适配器及其所选位置的任何信息。请进一步调试，并了解为什么mSelectedItem不更新您的UI。它不存储有关适配器及其所选位置的任何信息，因为它不是适配器的角色，而是RecyclerView本身（或其父项）…像一个符咒一样工作<代码>回收视图
有自己的。。。从Fragment的生命周期来看，似乎在所有视图的恢复安装状态之前调用了创建的
onActivityCreated
。@Selvin它不存储关于适配器及其所选位置的任何信息。请进一步调试，并了解为什么mSelectedItem不更新您的UI。它不存储有关适配器及其所选位置的任何信息，因为它不是适配器的角色，而是RecyclerView本身（或其父项）…像一个符咒一样工作。。。