1. List of Items in Spinner
Open “res/values/strings.xml” file, define the list of items that will display in Spinner (dropdown list).

======= File : res/values/strings.xml =============

[tpcode] 
<?xml version="1.0" encoding="utf-8"?>
<resources>

    <string name="app_name">MyAndroidApp</string>
    <string name="country_prompt">Choose a country</string>

    <string-array name="country_arrays">
        <item>Malaysia</item>
        <item>United States</item>
        <item>Indonesia</item>
        <item>France</item>
        <item>Italy</item>
        <item>Singapore</item>
        <item>New Zealand</item>
        <item>India</item>
    </string-array>

</resources> 
[/tpcode] 

2. Spinner (DropDown List)
Open “res/layout/main.xml” file, add two spinner components and a button.
    In “spinner1”, the “android:entries” represents the selection items in spinner.
    In “spinner2”, the selection items will be defined in code later.

============== File : res/layout/main.xml ==============

[tpcode] <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <Spinner
        android:id="@+id/spinner1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:entries="@array/country_arrays"
        android:prompt="@string/country_prompt" />

    <Spinner
        android:id="@+id/spinner2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

    <Button
        android:id="@+id/btnSubmit"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Submit" />

</LinearLayout> 
[/tpcode] 

3. Code Code
Read the code and also code’s comment, it should be self-explanatory.

============== File : MyAndroidAppActivity.java ========


[tpcode] package com.mkyong.android;

import java.util.ArrayList;
import java.util.List;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.Spinner;
import android.widget.Toast;

public class MyAndroidAppActivity extends Activity {

  private Spinner spinner1, spinner2;
  private Button btnSubmit;

  @Override
  public void onCreate(Bundle savedInstanceState) {
	super.onCreate(savedInstanceState);
	setContentView(R.layout.main);

	addItemsOnSpinner2();
	addListenerOnButton();
	addListenerOnSpinnerItemSelection();
  }

  // add items into spinner dynamically
  public void addItemsOnSpinner2() {

	spinner2 = (Spinner) findViewById(R.id.spinner2);
	List<String> list = new ArrayList<String>();
	list.add("list 1");
	list.add("list 2");
	list.add("list 3");
	ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(this,
		android.R.layout.simple_spinner_item, list);
	dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
	spinner2.setAdapter(dataAdapter);
  }

  public void addListenerOnSpinnerItemSelection() {
	spinner1 = (Spinner) findViewById(R.id.spinner1);
	spinner1.setOnItemSelectedListener(new CustomOnItemSelectedListener());
  }

  // get the selected dropdown list value
  public void addListenerOnButton() {

	spinner1 = (Spinner) findViewById(R.id.spinner1);
	spinner2 = (Spinner) findViewById(R.id.spinner2);
	btnSubmit = (Button) findViewById(R.id.btnSubmit);

	btnSubmit.setOnClickListener(new OnClickListener() {

	  @Override
	  public void onClick(View v) {

	    Toast.makeText(MyAndroidAppActivity.this,
		"OnClickListener : " +
                "\nSpinner 1 : "+ String.valueOf(spinner1.getSelectedItem()) +
                "\nSpinner 2 : "+ String.valueOf(spinner2.getSelectedItem()),
			Toast.LENGTH_SHORT).show();
	  }

	});
  }
} 
[/tpcode] 

========= File : CustomOnItemSelectedListener.java ============

[tpcode] package com.mkyong.android;

import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.Toast;

public class CustomOnItemSelectedListener implements OnItemSelectedListener {

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

  @Override
  public void onNothingSelected(AdapterView<?> arg0) {
	// TODO Auto-generated method stub
  }

}[/tpcode]