get index from ArrayList<HashMap<String, String>>

Question

I am building music player app for that I gathering data from SDcard which downloaded from the server and save files name into ArrayList

private ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();

Now the problem is I want to play mp3 file according to the user click on recycler item so for that, I want index number for the particular name.

How can I get an index for passing name of the mp3 file??

/**
     * Function to read all mp3 files from sdcard
     * and store the details in ArrayList
     */
    public ArrayList<HashMap<String, String>> getPlayList() {
        File home = new File(MEDIA_PATH);

        if (home.listFiles(new FileExtensionFilter()).length > 0) {
            for (File file : home.listFiles(new FileExtensionFilter())) {
                HashMap<String, String> song = new HashMap<String, String>();
                song.put("songTitle", file.getName().substring(0, (file.getName().length() - 4)));
                song.put("songPath", file.getPath());

                Log.d(TAG, "getPlayList() called title = "+file.getName().substring(0, (file.getName().length() - 4))+"  Path = "+file.getPath());
                // Adding each song to SongList
                songsList.add(song);
            }
        }
        // return songs list array
        return songsList;
    }

I advise you to make a Song class instead of storing properties in a HashMap — Tim
– Tim, Commented May 4, 2017 at 9:22
yes, POJO would be a good option but I already implemented HashMap so now it will take a time to implement and changes in all classes. — Arpit Patel
– Arpit Patel, Commented May 4, 2017 at 9:28

Tim · Accepted Answer · 2017-05-04 09:29:40Z

2

With your construction, you could loop over the list to find the map you need

int indexForSongName(String songName) {
    ArrayList<HashMap<String, String>> playlist = getPlayList();

    for (int i = 0; i < playlist.size(); i++) {
        HashMap<String, String> map = playlist.get(i);
        if (map.containsValue(songName)) { // Or map.getOrDefault("songTitle", "").equals(songName);
            return i;
        }
    }

    return -1; // Not found.
}

That said, I advise you to make a Song class instead of storing properties in a HashMap. It is good practice and it would make tasks such as these easier.

answered May 4, 2017 at 9:29

Tim

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2 Comments

Arpit Patel Over a year ago

i will try your answer and let you know

Arpit Patel Over a year ago

Thank you, genius its work like charm and I will remember your advice in future

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