HelloSwing - SWT 1 Tut 3 Example

HelloSwing.java

import java.awt.*;
import java.awt.image.*;
import java.io.File;
import java.io.IOException;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.ImageIcon;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.imageio.*;

public class HelloSwing {

  	/* Depends on two images "House.png" and "Car.png" to be existing in images/ under the project root directory. 
  	Such can be found at https://www.iconfinder.com/search/?q=house. */
	private static final String[] AVAILABLE_IMAGES = {"House", "Car"};
	private static final String IMAGES_BASE_PATH = "images/";
	private static final String IMAGE_TYPE = ".png";
	
	private static JLabel imageContainer;
	private static JComboBox imageDropdown;
	
	public static void main(String[] args) {
		/* Ideally the GUI should run in a separate Thread to prevent it from getting blocked by expensive
		business logic operations. Use javax.swing.SwingUtilities.invokeLater(), pass it a new Runnable and override run method. */
		JFrame frame = new JFrame("Hello Swing");
		frame.setSize(400, 200);
		frame.setLayout(new BorderLayout());
		
		imageDropdown = new JComboBox(AVAILABLE_IMAGES);
		imageDropdown.setSelectedIndex(0);
		imageDropdown.addActionListener(new ActionListener() {

			@Override
			public void actionPerformed(ActionEvent e) {	
				updateIcon();
			}
			
		});
		
		imageContainer = new JLabel();
		imageContainer.setHorizontalAlignment(JLabel.CENTER);
		updateIcon();
		
		frame.add(imageDropdown, BorderLayout.PAGE_START);
		frame.add(imageContainer, BorderLayout.PAGE_END);
		
		// Don't forget
		frame.setVisible(true);
	}
	
	private static void updateIcon() {
		imageContainer.setIcon(loadImageIcon(AVAILABLE_IMAGES[imageDropdown.getSelectedIndex()]));
	}
	
	private static ImageIcon loadImageIcon(String name) {
		BufferedImage img = null;

		// Don't do this - never just ignore an exception 
		try {
			img = ImageIO.read(new File(IMAGES_BASE_PATH + name + IMAGE_TYPE));
		} catch (IOException e) {
			e.printStackTrace();
		}
		
		return new ImageIcon(img);
	}
}