updating/refreshing List with custom ListAdapter

Question

I am aware that there are plenty of similar questions, but they all have in common, that their solutions dont work with my list :(

I am trying to get my userList refreshing itself via the custom ArrayAdapter, when the database-contents are changed. In my case when i reset();

here my snippets (partial code): MainActivity.java

public class MainActivity extends ListActivity {
    private MyUserListAdapter myUserlistAdapter; 
    public ArrayList<User> myUserList = new ArrayList<User>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //shortened the list-filling. but it works properly!
        User user = db.readUser(int);
        myUserList.add(user);
        myUserlistAdapter = new MyUserListAdapter(this, R.layout.row_main, myUserList);
        setListAdapter(myUserlistAdapter);

        //now when reset-button is hit, the listview should refresh itself
         bReset.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                 //this is what is posted in most questions, but it does nothing for me
                 //myUserlistAdapter.notifyDataSetChanged();
                 //getListView().invalidateViews();
            } });

and here myUserListAdapter.java:

public class MyUserListAdapter extends ArrayAdapter<User>{

private Context context;
private ArrayList<User> userList;

public MyUserListAdapter(Context context,
        int textViewResourceId, ArrayList<User> userList) {
    super(context, textViewResourceId, userList);

    this.context = context;
    this.userList = userList;
}

public View getView(int position, View v, ViewGroup parent) {

    if (v == null) {
        LayoutInflater li = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        v = li.inflate(R.layout.row_main, null);
    }

    User user = getItem(position);

    TextView tvUser = (TextView) v.findViewById(R.id.tvUser);
    ImageView ivVoted = (ImageView) v.findViewById(R.id.ivVoted);

    tvUser.setText(user.getName());

    //abfrage ob hasVoted() = true muss noch eingebaut werden.
    if (user.getVoted().equals("1"))
        ivVoted.setImageResource(R.drawable.redcheck);
    else
        ivVoted.setImageResource(R.drawable.greencheck);
    return v;
}   
}

User.java is just a simple object-class. think its not the troublemaker here!

any help is appreciated!!! thx :-)

Answer 1

I am trying to get my userList refreshing itself via the custom ArrayAdapter, when the database-contents are changed.

Since you are using ArrayAdapter and not CursorAdapter when you update data in database your adapter won't refresh itself. Whenever you want to update ListView you need to provide new datasource for Adapter.

One possible solution is to create setter in adapter subclass that will change datasource of adapter.

Pseudo code:

/* setter in adapter subclass */
public void changeDataSource(ArrayList<User> newUserList) {
   this.userList = newUserList;
}

Then call adapter.notifyDataSetChanged(); for ListView update.