Easiest ListView Example

This is a simplest Android Example for Android ListView

Introduction:

Android ListView is a view group that displays a list of scrollable items.

Android provides ListView and ExpandableListView classes for displaying scrollable list of items.

Note 1: When creating your main activity , you can extend ListActivity to use the default ListView but make sure you declare it as,

<ListView

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_below="@+id/mainText"

android:id="@android:id/list"

Also, you can assign the list adapter as

setListAdapter(myAdapter);

Thats the only difference.

Note 2: Important: Though you have a  ArrayList of Strings as source for listview, whenever you use the ArrayAdapter it should be declared as ArrayAdapter<String>

Adapter:
An adapter manages the data model and adapts it to the individual entries in the widget. An adapter extends the BaseAdapter class.

Default Adapters:
Android provides default adapter implementations; the most important are ArrayAdapter and CursorAdapter. ArrayAdapter can handle data based on Arrays or java.util.List. SimpleCursorAdapter can handle database related data.


Step 1 : Create a layout file with ListView
Step 2 : In your Activity, access the ListView created in Step 1 and perform the possible desired actions

• Get ListView object from xml
• Defined Array values to show in ListView
• Define a new Adapter
• Assign adapter to ListView
• Implement ListView Item Click Listener

Step 1 : Create a layout file with ListView

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    tools:context=".MyListView">

    <ListView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/listview1"></ListView>

</RelativeLayout>




Step 2 :  In your Activity, access the ListView created in Step 1 and perform the possible desired actions.


public class MyListView extends Activity {
    ListView lv;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_my_list_view);

        lv = (ListView)findViewById(R.id.listview1);     // Get ListView object from xml

        String values[] = {"Jellybean","Kitkat","Lollipop"};  // Defined Array values to show in ListView

        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1, android.R.id.text1,values);   // Define a new Adapter

        lv.setAdapter(adapter);  // Assign adapter to ListView

        lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {    //Implement ListView Item Click Listener
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
                int position = i;

                String x = (String)lv.getItemAtPosition(i);

                Toast.makeText(getApplicationContext(),"the selected item is " +x+" and at postion "+position, Toast.LENGTH_LONG).show();;
            }
        });

    }



OutPut : 

Excellent Tutorial on Customized Adapter is available in 

http://www.codelearn.org/android-tutorial/android-listview