Spinner View android exam

The Spinner view displays an item at a time from a list and lets the users choose among them.
Add a new file to the res/layout folder and name it as spinner.xml and populate it with the following element:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
    <Spinner 
        android:id="@+id/spinner1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:drawSelectorOnTop="true" />        
 
</LinearLayout>

Add a new class to the src/net.learn2develop.AndroidViews folder and name it as SpinnerExample.java. Populate it as follows:

package net.learn2develop.AndroidViews;
 
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.Toast;
import android.widget.AdapterView.OnItemSelectedListener;
 
public class SpinnerExample extends Activity 
{
    String[] presidents = {
            "Dwight D. Eisenhower",
            "John F. Kennedy",
            "Lyndon B. Johnson",
            "Richard Nixon",
            "Gerald Ford",
            "Jimmy Carter",
            "Ronald Reagan",
            "George H. W. Bush",
            "Bill Clinton",
            "George W. Bush",
            "Barack Obama"
    };
 
    Spinner s1;
 
    @Override    
    public void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.spinner);
 
        s1 = (Spinner) findViewById(R.id.spinner1);
 
        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
            android.R.layout.simple_spinner_item, presidents);
 
        s1.setAdapter(adapter);
        s1.setOnItemSelectedListener(new OnItemSelectedListener()
        {
            public void onItemSelected(AdapterView<?> arg0, 
            View arg1, int arg2, long arg3) 
            {
                int index = s1.getSelectedItemPosition();
                Toast.makeText(getBaseContext(), 
                    "You have selected item : " + presidents[index], 
                    Toast.LENGTH_SHORT).show();                
            }
 
            public void onNothingSelected(AdapterView<?> arg0) {}
        });
    }
}

The above program creates an ArrayAdapter object and associates it with the Spinner view. When an item in the Spinner view is selected, you will use the Toast class to display the item selected.
Modify the AndroidManifest.xml file to register the new activity:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="net.learn2develop.AndroidViews"
      android:versionCode="1"
      android:versionName="1.0.0">
    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".ViewsActivity"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
 
        <activity android:name=".SpinnerExample"
                  android:label="@string/app_name" />
 
    </application>
</manifest>

Modify the ViewsActivity.java file to start the SpinnerExample activity:

package net.learn2develop.AndroidViews;
 
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
 
public class ViewsActivity extends Activity 
{
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);  
 
        startActivity(new Intent(this, SpinnerExample.class));
 
    }
}

Press F11 to debug the application on the Android emulator. Figure 6 shows the Spinner view in action.

Figure 6: The Spinner view in action

Instead of displaying the items in the ArrayAdapter as a simple list, you can also display them using radio buttons. To do so, modify the second parameter in the constructor of the ArrayAdapter class:

ArrayAdapter<String> adapter  = new ArrayAdapter<String>(
            this,
            android.R.layout.simple_spinner_dropdown_item, 
            presidents);

Figure 7 shows the new appearance of the Spinner view.

Figure 7: The Spinner view