MainActivity.java

package com.pinecone.technology.mcommerce.learning.android.chapter10.spinner;

import android.app.ActionBar;
import android.app.Activity;
import android.app.Fragment;
import android.os.Bundle;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;

public class MainActivity extends Activity implements
		ActionBar.OnNavigationListener {

	/**
	 * The serialization (saved instance state) Bundle key representing the
	 * current dropdown position.
	 */

	private static final String STATE_SELECTED_NAVIGATION_ITEM = "selected_navigation_item";

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

		// Set up the action bar to show a dropdown list.
		final ActionBar actionBar = getActionBar();
		actionBar.setDisplayShowTitleEnabled(false);
		actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_LIST);

		final String[] dropdownValues = getResources().getStringArray(
				R.array.dropdown);

		// Specify a SpinnerAdapter to populate the dropdown list.
		ArrayAdapter<String> adapter = new ArrayAdapter<String>(
				actionBar.getThemedContext(),
				android.R.layout.simple_spinner_item, android.R.id.text1,
				dropdownValues);

		adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

		// Set up the dropdown list navigation in the action bar.
		actionBar.setListNavigationCallbacks(adapter, this);

		// Use getActionBar().getThemedContext() to ensure
		// that the text color is always appropriate for the action bar
		// background rather than the activity background.
	}

	@Override
	public void onRestoreInstanceState(Bundle savedInstanceState) {
		// Restore the previously serialized current dropdown position.
		if (savedInstanceState.containsKey(STATE_SELECTED_NAVIGATION_ITEM)) {
			getActionBar().setSelectedNavigationItem(
					savedInstanceState.getInt(STATE_SELECTED_NAVIGATION_ITEM));
		}
	}

	@Override
	public void onSaveInstanceState(Bundle outState) {
		// Serialize the current dropdown position.
		outState.putInt(STATE_SELECTED_NAVIGATION_ITEM, getActionBar()
				.getSelectedNavigationIndex());
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		getMenuInflater().inflate(R.menu.activity_main, menu);
		return true;
	}

	@Override
	public boolean onNavigationItemSelected(int position, long id) {
		// When the given dropdown item is selected, show its contents in the
		// container view.
		Fragment fragment = new DummySectionFragment();
		Bundle args = new Bundle();
		args.putInt(DummySectionFragment.ARG_SECTION_NUMBER, position + 1);
		fragment.setArguments(args);
		getFragmentManager().beginTransaction()
				.replace(R.id.container, fragment).commit();
		return true;
	}

	/**
	 * A dummy fragment
	 */

	public static class DummySectionFragment extends Fragment {

		public static final String ARG_SECTION_NUMBER = "placeholder_text";

		@Override
		public View onCreateView(LayoutInflater inflater, ViewGroup container,
				Bundle savedInstanceState) {
			TextView textView = new TextView(getActivity());
			textView.setGravity(Gravity.CENTER);
			textView.setText("SPINNER"+Integer.toString(getArguments().getInt(
					ARG_SECTION_NUMBER)));
			return textView;
		}
	}

}