切换Fragment时RecyclerView列表项重复翻倍问题求助

问题原因 #

你的HomeFragment中，songsList是Fragment的成员变量，每次切换回HomeFragment时，onCreateView方法会被重新执行，而你在查询歌曲前没有清空旧的列表数据，直接往原列表中追加新查询到的歌曲，导致列表项每次切换都翻倍。另外，代码中未关闭Cursor，存在内存泄漏风险。

解决方案 #

方案1：每次查询前清空列表 #

在查询MediaStore之前，先调用songsList.clear()清空旧数据，确保每次加载都是全新的歌曲列表：

修改后的HomeFragment代码：

public class HomeFragment extends Fragment {

    ArrayList<AudioModel> songsList = new ArrayList<>();
    RecyclerView recyclerView;
    TextView noMusicTextView;

    @SuppressLint("MissingInflatedId")
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_home, container, false);

        recyclerView = view.findViewById(R.id.recycler_view);
        noMusicTextView = view.findViewById(R.id.noSongs);

        // 先清空旧列表
        songsList.clear();

        String[] projection = {
                MediaStore.Audio.Media.TITLE,
                MediaStore.Audio.Media.DATA,
                MediaStore.Audio.Media.DURATION,
        };

        String selection = MediaStore.Audio.Media.IS_MUSIC + " !=0";
        Cursor cursor = null;
        try {
            cursor = getActivity().getContentResolver().query(
                    MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,
                    projection,
                    selection,
                    null,
                    null
            );
            if (cursor != null) {
                while (cursor.moveToNext()) {
                    AudioModel songData = new AudioModel(
                            cursor.getString(1),
                            cursor.getString(0),
                            cursor.getString(2)
                    );
                    if (new File(songData.getPath()).exists()) {
                        songsList.add(songData);
                    }
                }
            }
        } finally {
            // 关闭Cursor，避免内存泄漏
            if (cursor != null) {
                cursor.close();
            }
        }

        if (songsList.size() == 0) {
            noMusicTextView.setVisibility(View.VISIBLE);
        } else {
            recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
            recyclerView.setAdapter(new MusicListAdapter(songsList, getContext()));
        }

        return view;
    }
}

方案2：只加载一次歌曲数据（优化） #

如果本地歌曲不会频繁变动，可以只在Fragment创建时加载一次数据，避免每次切换都重复查询MediaStore：

修改后的HomeFragment代码：

public class HomeFragment extends Fragment {

    ArrayList<AudioModel> songsList = new ArrayList<>();
    RecyclerView recyclerView;
    TextView noMusicTextView;
    // 标记是否已加载过歌曲数据
    private boolean isDataLoaded = false;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // 在onCreate中加载数据，只执行一次
        loadSongsData();
    }

    private void loadSongsData() {
        if (isDataLoaded) return;
        songsList.clear();

        String[] projection = {
                MediaStore.Audio.Media.TITLE,
                MediaStore.Audio.Media.DATA,
                MediaStore.Audio.Media.DURATION,
        };

        String selection = MediaStore.Audio.Media.IS_MUSIC + " !=0";
        Cursor cursor = null;
        try {
            cursor = getActivity().getContentResolver().query(
                    MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,
                    projection,
                    selection,
                    null,
                    null
            );
            if (cursor != null) {
                while (cursor.moveToNext()) {
                    AudioModel songData = new AudioModel(
                            cursor.getString(1),
                            cursor.getString(0),
                            cursor.getString(2)
                    );
                    if (new File(songData.getPath()).exists()) {
                        songsList.add(songData);
                    }
                }
            }
        } finally {
            if (cursor != null) {
                cursor.close();
            }
        }
        isDataLoaded = true;
    }

    @SuppressLint("MissingInflatedId")
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_home, container, false);

        recyclerView = view.findViewById(R.id.recycler_view);
        noMusicTextView = view.findViewById(R.id.noSongs);

        if (songsList.size() == 0) {
            noMusicTextView.setVisibility(View.VISIBLE);
        } else {
            recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
            recyclerView.setAdapter(new MusicListAdapter(songsList, getContext()));
        }

        return view;
    }
}

额外注意点 #

• 确保AudioModel类的equals方法正确实现（如果后续需要去重操作）。
• 访问MediaStore需要申请READ_EXTERNAL_STORAGE权限（Android 13及以上需要READ_MEDIA_AUDIO权限），记得在Manifest中声明并动态申请。

内容的提问来源于stack exchange，提问作者Dragon 313