如何将 Arraylist 保存到文件? [英] How to save an Arraylist to file?

问题描述

我想将数组列表写入文件.但我不知道怎么做.也许你可以帮助我.如何将其保存到文件中?到目前为止代码还好吗?也许你有足够的时间来浏览它.非常感谢，文岑兹

I want to write the arraylist to a file. But I don't know how. Maybe you can help me. How can I save it to a File? And is the code good so far? Maybe you've enough time to look through it. Thanks a lot, Vinzenz

public class SongsManager {

final String MEDIA_PATH = Environment.getExternalStorageDirectory()
        .getPath() + "/";
private ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();
private String mp3Pattern = ".mp3";
private String mp4Pattern = ".mp4";
private String MP3Pattern = ".MP3";
private String MP4Pattern = ".MP4";

// Constructor
public SongsManager() {

}

/**
 * Function to read all mp3 files and store the details in
 * ArrayList
 * */
public ArrayList<HashMap<String, String>> getPlayList() {
    System.out.println(MEDIA_PATH);
    if (MEDIA_PATH != null) {
        File home = new File(MEDIA_PATH);
        File[] listFiles = home.listFiles();
        if (listFiles != null && listFiles.length > 0) {
            for (File file : listFiles) {
                System.out.println(file.getAbsolutePath());
                if (file.isDirectory()) {
                    scanDirectory(file);
                } else {
                    addSongToList(file);
                }
            }
        }
    }
    // return songs list array
    return songsList;
}

private void scanDirectory(File directory) {
    if (directory != null) {
        File[] listFiles = directory.listFiles();
        if (listFiles != null && listFiles.length > 0) {
            for (File file : listFiles) {
                if (file.isDirectory()) {
                    scanDirectory(file);
                } else {
                    addSongToList(file);
                }

            }
        }
    }
}

private void addSongToList(File song) {
    if (song.getName().endsWith(mp3Pattern) || song.getName().endsWith(mp4Pattern) || song.getName().endsWith(MP4Pattern) || song.getName().endsWith(MP3Pattern)) {
        HashMap<String, String> songMap = new HashMap<String, String>();
        songMap.put("songTitle",
                song.getName().substring(0, (song.getName().length() - 4)));
        songMap.put("songPath", song.getPath());

        // Adding each song to SongList
        songsList.add(songMap);
    }
}
private void saveFiletoTXT() {
    try{
        java.io.FileOutputStream fos = new java.io.FileOutputStream("/sdcard/");
        java.io.ObjectOutputStream oos = new java.io.ObjectOutputStream(fos);

        oos.writeObject((java.util.ArrayList) songsList);
        oos.flush();
        fos.close();
        }
        catch(Exception e){}
}
}

推荐答案

虽然您实际上可以序列化 ArrayList，但我真的不认为您想要这样做.我认为使用 android.database.sqlite 包 将其内容存储在 SQLLite 中更有意义，如此处.

While you could literally serialize an ArrayList, I really don't think you want to do that. I think it makes more sense to store its contents in SQLLite using the android.database.sqlite package as described here.

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