ListView
Android ListView is a view which contains the group of items and displays in a scrollable list. ListView is implemented by importing android.widget.ListView class. ListView is a default scrollable which does not use other scroll view.
ListView uses Adapter classes which add the content from data source (such as string array, array, database etc) to ListView. Adapter bridges data between an AdapterViews and other Views (ListView, ScrollView etc).
Example of ListView
Let's implement a simple listview example.
Structure of listview project
activity_main.xml
First we need to drag and drop ListView component from palette to activity_main.xml file.
File: activity_main.xml
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="listview.example.com.listview.MainActivity">
<ListView
android:id="@+id/listView"
android:layout_width="match_parent"
android:layout_height="fill_parent"
/>
</android.support.constraint.ConstraintLayout>
Create an additional mylist.xml file in layout folder which contains view components displayed in listview.
mylist.xml
File: mylist.xml
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Medium Text"
android:textStyle="bold"
android:textAppearance="?android:attr/textAppearanceMedium"
android:layout_marginLeft="10dp"
android:layout_marginTop="5dp"
android:padding="2dp"
android:textColor="#4d4d4d"
/>
Now place the list of data in strings.xml file by creating string-array.
strings.xml
File:strings.xml
<string name="app_name">ListView</string>
<string-array name="array_technology">
<item>Android</item>
<item>Java</item>
<item>Php</item>
<item>Hadoop</item>
<item>Sap</item>
<item>Python</item>
<item>Ajax</item>
<item>C++</item>
<item>Ruby</item>
<item>Rails</item>
<item>.Net</item>
<item>Perl</item>
</string-array>
</resources>
Activity class
In java class we need to add adapter to listview using setAdapter() method of listview.
File: MainActivity.java
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
ListView listView;
TextView textView;
String[] listItem;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView=(ListView)findViewById(R.id.listView);
textView=(TextView)findViewById(R.id.textView);
listItem = getResources().getStringArray(R.array.array_technology);
final ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, android.R.id.text1, listItem);
listView.setAdapter(adapter);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int position, long l) {
// TODO Auto-generated method stub
String value=adapter.getItem(position);
Toast.makeText(getApplicationContext(),value,Toast.LENGTH_SHORT).show();
}
});
}
}
Output
