Android spinner widget.

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <Spinner
        android:id="@+id/main_animals"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

</LinearLayout>

MainActivity.java

package com.edinstudio.app.training.ui;

import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.Toast;

public class MainActivity extends ActionBarActivity implements
		OnItemSelectedListener {

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

		String[] animals = { "Panda", "Tiger", "Lion", "Elephant" };
		ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
				android.R.layout.simple_list_item_1, animals);
		Spinner spAnimals = (Spinner) findViewById(R.id.main_animals);
		spAnimals.setAdapter(adapter);
		spAnimals.setOnItemSelectedListener(this);
	}

	@Override
	public void onItemSelected(AdapterView<?> parent, View view, int pos,
			long id) {
		Toast.makeText(this, "Selected: " + parent.getItemAtPosition(pos),
				Toast.LENGTH_SHORT).show();
	}

	@Override
	public void onNothingSelected(AdapterView<?> parent) {

	}
}