MainActivity.java

public class MainActivity extends AppCompatActivity {

    ListView listView;

    MyAdapter adapter;

    List<MyData> data;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        listView = findViewById(R.id.list_view);
      
        data = new ArrayList<>();
        data.add(new MyData("123", Color.GREEN));
        data.add(new MyData("456", Color.RED));
        data.add(new MyData("789", Color.BLUE));

        adapter = new ArrayAdapter<>(this, /* your layout here */, data);
        listView.setAdapter(adapter);
    }

    // this method sets the color of a certain item and notifies the adapter that that the data has changed
    public void setColor(int position, int color) {
        MyData item = data.get(position);
        item.setColor(color);
        adapter.notifyDataSetChanged();
    }
}

MyAdapter.java

public class MyAdapter extends BaseAdapter {

    private LayoutInflater inflater;

    private int layoutResource;

    private List<MyData> data;

    public MyAdapter(Context context, int layoutResource, List<MyData> data) {
        inflater = LayoutInflater.from(context);
        this.data = data;
        this.layoutResource = layoutResource;
    }

    @Override
    public int getCount() {
        return data.size();
    }

    @Override
    public MyData getItem(int position) {
        return data.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View view = createView(convertView, parent);
        MyData data = getItem(position);

        // TO DO: setup your view here such as setting the color, and the text

        return view;
    }

    private View createView(View convertView, ViewGroup parent) {
        if (convertView == null) {
            return inflater.inflate(layoutResource, parent, false);
        } else {
            return convertView;
        }
    }

    public static class MyData {

        private final String value;

        private final int color;

        public MyData(String value, int color) {
            this.value = value;
            this.color = color;
        }
      
        public void setColor(int color) {
            this.color = color;
        }
    }
}