FragmentStatePagerAdapter 处理 getItem() 位置

我尝试了这个，但错误的列表被绑定到回收器视图。我也尝试过 SparseArray，即使这样也不起作用。当我启动 Mainactivity 时，getItem() 被调用两次。退回的仓位如何处理？ 我尝试返回 viewpager currentItem，即使这样也不起作用。

主要活动

public class PagerAdapter extends FragmentStatePagerAdapter {
    int mNumOfTabs;


    public PagerAdapter(android.support.v4.app.FragmentManager fragmentManager, int tabCount) 
    {
        super(fragmentManager);
        this.mNumOfTabs = tabCount;    
    } 

    @Override
    public Fragment getItem(int position) {

        return Categories_Fragment.newInstance(position);

    }

    @Override
    public int getCount() {
        return mNumOfTabs;
    }

}

类别_片段

public class Categories_Fragment extends Fragment 
{
private RecyclerView lvMessages; 
private int fromPage;


public static Categories_Fragment newInstance(int num) {
    Categories_Fragment f = new Categories_Fragment();

    // Supply num input as an argument.
    Bundle args = new Bundle();
    args.putInt("from", num);
    f.setArguments(args);

    return f; 
}


@Override
public void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    fromPage = getArguments().getInt("from"); 


}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {      
    // TODO Auto-generated method stub  
    View rootView = inflater.inflate(R.layout.categories_filter, container, false); 
    lvMessages    = (RecyclerView)rootView.findViewById(R.id.lv_categories_filter);

    LinearLayoutManager x =  new LinearLayoutManager(getActivity()); 
    x.setOrientation(LinearLayoutManager.VERTICAL); 

    lvMessages.setLayoutManager(x);   


    return rootView; 
}


@Override
public void onActivityCreated(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onActivityCreated(savedInstanceState);

    // bind different data to the RecyclerView based on fromPage value. 

    }

}

这可能是最关键的......

@Override
public void setUserVisibleHint(boolean isVisible) {
    super.setUserVisibleHint(isVisible);
    if (isVisible) {
        // bind to stuff using value of fromPage from here
    }
}

公共无效setUserVisibleHint（布尔isVisibleToUser） http://developer.android.com/reference/android/support/v4/app/Fragment.html#setUserVisibleHint%28boolean%29: 向系统设置有关此片段的 UI 当前是否对用户可见的提示。此提示默认为 true，并且在片段实例状态保存和恢复过程中保持不变。

问题可能是什么（如果我正确理解你的问题）是寻呼机正在传递其“最后已知”位置，这并不一定意味着当前在设备屏幕上显示的片段的位置。

UPDATE:这是一个完整的示例，其中 ViewPager 处理相同的片段，但传递给它的数据不同：

public class ViewPagerAdapter extends FragmentStatePagerAdapter {

    private JSONArray itemsArray;
    private int fragmentId;

    public ViewPagerAdapter(JSONArray itemsArray, int fragmentId, FragmentManager manager) {
        super(manager);
        this.itemsArray = itemsArray;
        this.fragmentId = fragmentId;
    }

    @Override
    public Fragment getItem(int position) {
        JSONObject itemObject = new Listing(itemsArray, position).getObject();
        Bundle bundle = new Bundle();
        bundle.putString("item_object", itemObject.toString());
        bundle.putInt("item_position", position);
        bundle.putInt("total_items", getCount());
        bundle.putInt("fragment_Id", fragmentId);
        Fragment fragment = new ListingFragment();
        fragment.setArguments(bundle);
        return fragment;
    }

    @Override
    public int getCount() {
        return itemsArray.length();
    }

}

这是列表片段（减去不重要的部分）：

public class ListingFragment extends Fragment {

    private Listing listing;

    private String itemObject;
    private int itemPosition;
    private int totalItems;
    private int fragmentId;

    public ListingFragment() { }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Bundle bundle = getArguments();
        itemObject = bundle.getString("item_object");
        itemPosition = bundle.getInt("item_position");
        totalItems = bundle.getInt("total_items");
        fragmentId = bundle.getInt("fragment_Id");
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
        View view = ...
        // nothing special to see here, just the usual stuff
        return view;
    }

    @Override
    public void setUserVisibleHint(boolean isVisible) {
        super.setUserVisibleHint(isVisible);
        if (isVisible) {
            // send fragmentID to wherever you want to use it
            // such as your recyclerview/adapter from here
         }
     }

}

我希望这个例子能给我一些启发，我知道它对我一定有用。