增加Recyclerview的项目，同时在Tab视图中交换视图寻呼机

Question

我创建了一个带有四个选项卡的tabview，并在此选项卡视图中使用viewpager。在视图寻呼机中，我设置了recyclerview。我给每个recylerview列出了五个物品清单，每个recyclerview显示5个物品，但是交换这些物品变成了双重物品。

我主要的Java活动

public class WorldMAp extends AppCompatActivity { 
private TabLayout tabLayout; 
private ViewPager viewPager; 
@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.worldmap_activity); 

    viewPager = (ViewPager) findViewById(R.id.viewpager); 
    setupViewPager(viewPager); 

    tabLayout = (TabLayout) findViewById(R.id.tabs); 
    tabLayout.setupWithViewPager(viewPager); 

} 
private void setupTabIcons() { 
    tabLayout.getTabAt(0).setIcon(R.drawable.iconmap); 
    tabLayout.getTabAt(1).setIcon(R.drawable.iconmap); 
    tabLayout.getTabAt(2).setIcon(R.drawable.iconmap); 
} 
private void setupViewPager(ViewPager viewPager) { 
    ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager()); 
    adapter.addFragment(new Tab1Fragment(), "Countries"); 
    adapter.addFragment(new Tab2Fragment(), "RIVERS"); 
    adapter.addFragment(new Tab3Fragment(), "PEAKS"); 
    adapter.addFragment(new Tab4Fragment(), "WONDERS"); 
    viewPager.setAdapter(adapter); 
} 
class ViewPagerAdapter extends FragmentPagerAdapter { 
    private final List<Fragment> mFragmentList = new ArrayList<>(); 
    private final List<String> mFragmentTitleList = new ArrayList<>(); 

    public ViewPagerAdapter(FragmentManager manager) { 
     super(manager); 
    } 

    @Override 
    public Fragment getItem(int position) { 
     return mFragmentList.get(position); 
    } 

    @Override 
    public int getCount() { 
     return 4; 
    } 

    public void addFragment(Fragment fragment, String title) { 
     mFragmentList.add(fragment); 
     mFragmentTitleList.add(title); 
    } 

    @Override 
    public CharSequence getPageTitle(int position) { 
     return mFragmentTitleList.get(position); 
    } 
} 
} 

回收站视图适配器

public class Country_Adapter extends 
RecyclerView.Adapter<Country_Adapter.MyViewHolder> { 

private List<Country> countryList; 

public class MyViewHolder extends RecyclerView.ViewHolder { 
    public TextView title, genre; 
    public ImageView imageView; 

    public MyViewHolder(View view) { 
     super(view); 
     title = (TextView) view.findViewById(R.id.title); 
     genre = (TextView) view.findViewById(R.id.genre); 
     imageView=(ImageView)view.findViewById(R.id.image); 

    } 
} 


public Country_Adapter(List<Country> countryList) { 
    this.countryList = countryList; 
} 

@Override 
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { 
    View itemView = LayoutInflater.from(parent.getContext()) 
      .inflate(R.layout.country_list, parent, false); 

    return new MyViewHolder(itemView); 
} 

@Override 
public void onBindViewHolder(MyViewHolder holder, int position) { 
    Country movie = countryList.get(position); 
    holder.title.setText(movie.getTitle()); 
    holder.genre.setText(movie.getGenre()); 
    holder.imageView.setBackgroundResource(R.drawable.share); 
} 

@Override 
public int getItemCount() { 
    return countryList.size(); 
} 
} 

标签视图

private List<Country> countryList = new ArrayList<>(); 
private RecyclerView recyclerView; 
private Country_Adapter mAdapter; 
ImageView imageView; 
@Nullable 
@Override 
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) { 
    View view = inflater.inflate(R.layout.tab1_fragment,container,false); 

    recyclerView = (RecyclerView) view.findViewById(R.id.recycler_view); 

    mAdapter = new Country_Adapter(countryList); 
    RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(getActivity()); 
    recyclerView.setLayoutManager(mLayoutManager); 
    recyclerView.setItemAnimator(new DefaultItemAnimator()); 
    recyclerView.setAdapter(mAdapter); 
    prepareMovieData(); 
return view; 
} 
private void prepareMovieData() { 
    Country country = new Country("Mad Max: Fury Road", "Action & Adventure"); 
    countryList.add(country); 

    Country country1 = new Country("Mad Max: Fury Road", "Action & Adventure"); 
    countryList.add(country1); 
    Country country2 = new Country("Mad Max: Fury Road", "Action & Adventure"); 
    countryList.add(country2); 
    Country country3 = new Country("Mad Max: Fury Road", "Action & Adventure"); 
    countryList.add(country3); 
    Country country4 = new Country("Mad Max: Fury Road", "Action & Adventure"); 
    countryList.add(country4); 


} 

我如何从这些自动增加项目预防？

Answer 1

默认情况下，ViewPage可以容纳2个片段，并且如果在返回1时返回4，则会使用4，如果调用onCreate第一个片段，反之亦然。以防止这种使用

 mViewPager.setOffscreenPageLimit(4); 

setOffscreenPageLimit将维护堆栈中的所有4片段并将阻止娱乐。