Customed ArrayAdapter

Question

I created a class called Categoria, it has two attributes (String nombre, int id).

I created an ArrayList with elements of type Categoria.

When I show the ArrayList on a ListView, I get this:

Instead of this, I want the attribute nombre, that is a String, to be shown. The ArrayAdapter must be of the type Categoria, not String.

How can I do this? Maybe creating a customed adapter?

Here is a piece of the code:

public class MainActivity extends AppCompatActivity {

private ArrayList<Categoria> lista;
private ArrayAdapter<Categoria> adaptador;
private ListView view_lista;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    adaptador = new ArrayAdapter<Categoria>(this, android.R.layout
            .simple_list_item_1, lista);
    view_lista = (ListView)findViewById(R.id.view_lista);
    view_lista.setAdapter(adaptador);

And this is the simple_list_item_1 layout:

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@android:id/text1"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceListItemSmall"
    android:gravity="center_vertical"
    android:paddingStart="?android:attr/listPreferredItemPaddingStart"
    android:paddingEnd="?android:attr/listPreferredItemPaddingEnd"
    android:minHeight="?android:attr/listPreferredItemHeightSmall" />

Thanks :)

Id recommend using a custom adapter here – Zach Oct 29 '16 at 19:15 — Zach, Oct 29 '16 at 19:15

score 2 · Answer 1 · edited May 23 '17 at 11:46

adaptador = new ArrayAdapter<Categoria>(this, android.R.layout
            .simple_list_item_1, lista);

Here you pass your ArrayList (lista) to the adapter. The adapter will then just call the toString() method of each Object in the ArrayList.

So you could override the toString() method in your Categoria class to return the nombre attribute.

@Override
public String toString(){
   return this.nombre;
}

You could also create an ArrayList<String> instead of your ArrayList<Categoria> and only add the nombre attributes (instead of the whole Categoria object). Another option would be to create your own ArrayAdapter and customize what is shown in the getView() method.

Have a look at this question

score 1 · Answer 2 · answered Oct 29 '16 at 19:16

1

The easiest way is passing only ArrayList to the adapter.

If you want to pass Categoria object to your adapter, you must write your own custom adapter for it.

The link contains pretty good examples about that scenario.

answered Oct 29 '16 at 19:16

Efe Budak

659
5
27

score 1 · Accepted Answer · answered Oct 29 '16 at 19:22

By default, ArrayAdapter will display the text returned by the toString method of your objects. In this simple case, you can simply override the toString method for Categoria and return the nombre field:

public class Categoria {
  ...

    @Override
    public String toString() {
        return this.nombre;
    }
}

If your application needs ever change and you require a more complicated layout, you can override the getView method of ArrayAdapter to bind data from Categoria to a more complicated view.

Customed ArrayAdapter

3 Answers3