Accessing and using custom Objects and ArrayList<Object> in different methods

Question

I am currently working on an app that will use many objects as information holders (music things - artist, song, id of album cover img, and another id of 2nd img).

I decided that it would be the best to create "Track" class and use it to make objects and store them in ArrayList.

I created the class, I created the list, but I'm having trouble with accessing it (I want to change the ImageViews and TextViews basing on current Track object).

Here's the Track Class: (Track.java separate)

public class Track {
private String mNameArtist;
private String mNameTrack;
private int mTabResource;
private int mCoverResource;

public Track(String nameArtist, String nameTrack, int tabResourceId, int coverResourceId){
    mNameArtist = nameArtist;
    mNameTrack = nameTrack;
    mTabResource = tabResourceId;
    mCoverResource = coverResourceId;
}
public String getArtistName() {
    return mNameArtist;
}
public String getTrackName() {
    return mNameTrack;
}
public int getTabResourceId() {
    return mTabResource;
}
public int getCoverResourceID() {
    return mCoverResource;
}}

And here's ArrayList declaration: (PlayActivity.java, inside onCreate method)

    ArrayList<Track> Tracks = new ArrayList<Track>();
    Tracks.add(new Track("Artist Name", "Track Name", R.drawable.tabtemplate, R.drawable.testcover));
    Tracks.add(new Track("Pink Floyd", "Comfortably Numb Solo 1", R.drawable.CNS1Tab, R.drawable.pink_floyd_the_wall));

There are more positions, but you get the idea.

Everything seems to work fine up to this point.

When I want to access it inside another method (even in the same PlayActivity.java) nothing happens or I see errors. I tried many different approaches but every single one fails. For example:

    Track.getTabResource();  // can't even use the method.
    Tracks.get(3);           // does not work as well.

I just can not use objects or that arraylist inside my methods. The "Tracks array" won't even show up in Android Studio when typing. Track does, but I can't access positions from Array.

So to sum up, is there any other way I can use my Objects (ArrayList) items inside other classes and methods?

Thank you for your help in advance.

Tracks is a local variable.. Use a field instead (like mNameArtist in Track) — user180100
– user180100, Commented Jun 25, 2017 at 18:05

OneCricketeer · Accepted Answer · 2017-06-25 18:29:32Z

0

Create List as instance variable and access through Object of that class.

public class PlayActivity {
        List<Track> tracks = new ArrayList<Track>();

        public void onCreate() {
            tracks.add(new Track("Artist Name", "Track Name", R.drawable.tabtemplate, R.drawable.testcover));
            tracks.add(
                    new Track("Pink Floyd", "Comfortably Numb Solo 1", R.drawable.CNS1Tab, R.drawable.pink_floyd_the_wall));
        }

        public List<Track> getAllTracks() {
            return Collections.unmodifiableList(tracks);
        }

        public Track getTrack(int index) {
            return tracks.get(index);

        }
    }

edited Jun 25, 2017 at 18:29

OneCricketeer

193k20 gold badges146 silver badges276 bronze badges

answered Jun 25, 2017 at 18:11

gati sahu

2,6512 gold badges12 silver badges16 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Qlak Over a year ago

Well, thank you mate! It helped a lot. Overally my code and everything was fine, I just made superstupid mistake and declared my ArrayList in the onCreate method, while it should be outside, alongside with the rest of the variables. I did not change it from ArrayList to the normal List thought, I'm not sure if it was necessary? Anyway it works perfect now, thank you for help. I'm stupid I did not notice it myself :D. Cheers!

Collectives™ on Stack Overflow

Accessing and using custom Objects and ArrayList<Object> in different methods

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related