视图重新添加到视图寻呼机中的片段

Question

我正在为Android制作一个画廊应用程序，我正面临一个问题：

我在MainActivity中创建了一个ViewPager，它有2个片段，一个用于图像，一个用于视频。每个片段都包含一个recyclerView，用于显示受尊重的媒体类型的存储桶。例如，在图像片段中，将有“相机”，“下载”等等的存储桶。我将onClick附加到Recycler视图中的项目，这些也正常工作。问题是：

每当设备的方向改变时，回收器视图中的桶（基本上是卡片视图）都是重复的。例如，如果片段最初包含2个文件夹“Camera”和“Downloads”，那么片段将有4个文件夹，2个用于“Camera”，2个用于“Downloads”，每次方向更改时都会发生这种复制。

MainActivity的代码：

public class MainActivity extends AppCompatActivity {
private static final int REQUEST_PERMISSIONS_CODE = 100;
ArrayList<FoldersModel> foldersModelArrayList = new ArrayList<>();


Toolbar toolbar;
ViewPager mainViewPager;
SpringIndicator indicator;
MainPagerAdapter mainPagerAdapter;

Context context;
HashMap<String, ArrayList<ImageModel>> map;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    context = this;
    map = new HashMap<>();

    root = findViewById(R.id.root);
    contentHamburger = findViewById(R.id.content_hamburger);
    toolbar = findViewById(R.id.mainActivityToolBar);

    setSupportActionBar(toolbar);
    mainViewPager = findViewById(R.id.mainViewPager);
    indicator = findViewById(R.id.indicator);

    if ((ContextCompat.checkSelfPermission(
            getApplicationContext(),
            Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED)) {
        if ((ActivityCompat.shouldShowRequestPermissionRationale(
                MainActivity.this,
                Manifest.permission.READ_EXTERNAL_STORAGE))) {

        } else {
            ActivityCompat.requestPermissions(MainActivity.this,
                    new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE, Manifest.permission.READ_EXTERNAL_STORAGE},
                    REQUEST_PERMISSIONS_CODE);
        }
    } else {
        loadImages();
    }

    mainPagerAdapter = new MainPagerAdapter(getSupportFragmentManager(), foldersModelArrayList);
    mainViewPager.setAdapter(mainPagerAdapter);
    indicator.setViewPager(mainViewPager);
}

@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    if (requestCode == REQUEST_PERMISSIONS_CODE) {
        for (int i = 0; i < grantResults.length; i++) {
            if (grantResults.length > 0 && grantResults[i] == PackageManager.PERMISSION_GRANTED) {
                loadImages();
            } else {
                Toast.makeText(MainActivity.this, "Permission Denied", Toast.LENGTH_LONG).show();
            }
        }
    }

    super.onRequestPermissionsResult(requestCode, permissions, grantResults);
}


public void loadImages() {
    //load images code, not really useful for this question
    //basically populates the folderModelArrayList       
}

public static class ImageFoldersFragment extends Fragment {

    public ImageFoldersFragment(){

    }

    public static ImageFoldersFragment newInstance(int position, ArrayList<FoldersModel> foldersModels) {
        ImageFoldersFragment fragment = new ImageFoldersFragment();
        Bundle bundle = new Bundle();
            bundle.putParcelableArrayList("foldersData", foldersModels);
        bundle.putInt("position", position);
        fragment.setArguments(bundle);
        return fragment;
    }

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_image, container, false);
        RecyclerView recyclerView = view.findViewById(R.id.imageFoldersRecyclerView);
        Bundle bundle = getArguments();
            ArrayList<FoldersModel> foldersModel = bundle.getParcelableArrayList("foldersData");
        recyclerView.setLayoutManager(new GridLayoutManager(getContext(),2));
        recyclerView.setAdapter(new FoldersAdapter(getContext(), MainActivity.foldersModelArrayList));

        recyclerView.addOnItemTouchListener(new ImageClickedListener(getContext(), new OnItemClickListener() {
            @Override
            public void onItemClick(View view, final int position) {
                Intent intent = new Intent(getContext(), SingleFolderActivity.class);
                intent.putParcelableArrayListExtra("data", MainActivity.foldersModelArrayList.get(position).getImageModelsList());
                intent.putExtra("bucket", MainActivity.foldersModelArrayList.get(position).getFoldersName());
                startActivity(intent);
            }
        }));

        return view;
    }
}

class MainPagerAdapter extends FragmentPagerAdapter {
    String[] tabs = {"Images", "Videos"};
    ArrayList<FoldersModel> foldersModelArrayList;

    public MainPagerAdapter(FragmentManager fm, ArrayList<FoldersModel> list) {
        super(fm);
        foldersModelArrayList = list;
    }

    @Override
    public Fragment getItem(int position) {
        ImageFoldersFragment fragment = ImageFoldersFragment.newInstance(position, foldersModelArrayList);
        return fragment;
    }

    @Override
    public int getCount() {
        return 2;
    }

    @Nullable
    @Override
    public CharSequence getPageTitle(int position) {
        return tabs[position];
    }
}

}

为什么会这样？有没有办法解决这个问题？非常感谢提前！

Answer 1

试试这个。

让foldersModelArrayList非静态。

在onCreate()中初始化它。