ListView

This project explain how to add and remove items from ListView, using the default and the custom layout.

The activity_main.xml have buttons to create and remove selected items, and two ListViews for the layouts.

Buttons Function:

• create item: create a new item in each list and refresh the view.
• remove item: remove selected items from the list and disable the remove button.

List items Function:

• Simple click: display message with the item information;
• Long click: select item from list and enable the remove button.
  • in the simple list only one item can be selected
  • in the custom list multiple items can be selected

custom_item_list.xml, which is the custom item layout, shows an image and text.

Simple List

To setup the listView, the following lines are important.

ListView listView = (ListView) findViewById(R.id.listDefault);
ArrayAdapter adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, arrayList);
listView.setAdapter(adapter);

The ArrayAdapter constructor is created with Context, layout id and a ArrayList parameters, in which the last the lists elements are placed.

By default, android.R.layout.simple_list_item_1 is a simple layout in which display a single text.

Instead of an arrayList variable created and appended to the constructor,new ArrayList<String>()can be appended directly. In this case, only the adapter can manage the items.

Then finally the listView need to bind the adapter.

listView.setAdapter(adapter);

When the ListView has its elements modified (not applied when a item is selected), the view needs to be refreshed by calling this method:

adapter.notifyDataSetChanged();

Interact with an item from the list

One click

This method is called when the ListView is clicked

listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
    @Override
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
        //do something
    }
});

which the position variable is the position of the list in the view. Or you can create a new class implementing the AdapterView.OnItemClickListener:

listView.setOnItemClickListener(new MyItemClicked());

Then:

class MyItemClicked implements AdapterView.OnItemClickListener{
    @Override
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
        //do something
    }
}

Long click

listView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
    @Override
    public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
        //do something
        return true;
    }
});

Which the value returned must be true if the callback consumed the long click (then the OnItemClick method does not run automatically after the OnItemLongClick executes when the finger is released). And like in the OnItemClickListener, you can create a class implementing the AdapterView.OnItemLongClickListener.

Select one item

To be able to select an item in the ListView needs to be set the selection mode and its color ().

listView.setChoiceMode(AbsListView.CHOICE_MODE_SINGLE);
listView.setSelector(android.R.color.holo_red_light); //setup the color when selected

Then when an item is clicked to able the select function add this line:

simpleListView.setSelected(true);

For some reason, disable the select function is not working to return to the click simple. When an item is clicked, it continues highlighted with the same color setted in the selector. The same happens if the choice mode is changed to CHOICE_MODE_NONE. For now, change the color to the previous one and calling listView.clearFocus() always when the highlight need to be disable works, but it is not beautiful. Need to find a better way.

Select multiple items (still working)

Custom List

For this example a custom layout item has an image and a text. The MyItem class will be responsible for storing these informations to put in the view.

public class MyItem{
        int icon;
        String title;

        MyItem(int icon, String title){
            this.icon = icon;
            this.title = title;
        }
    }

The CustomAdapter class is our custom adapter, which extends BaseAdapter. The BaseAdapter has the method getView() that takes care of the process of putting the information in their respective places in the layout.

public class CustomAdapter extends BaseAdapter {
    private Context context;
    private int layoutId;
    private ArrayList<MyItem> data;

    CustomAdapter(Context context, int layoutId, ArrayList<MyItem> data){
        this.context = context;
        this.data = data;
        this.layoutId = layoutId;
    }
    
    ...

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        if(convertView == null){
            LayoutInflater layoutInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = layoutInflater.inflate(layoutId, parent, false);
        }

        ((ImageView)convertView.findViewById(R.id.imageView)).setImageResource(data.get(position).icon);
        ((TextView)convertView.findViewById(R.id.text_title)).setText(data.get(position).text);

        return convertView;
    }
}