Java Swing

Image Credit: Wikipedia

Java Swing

• Developed in late 1990s
• Upgrade to
  Abstract Window Toolkit (AWT)
• Object-Oriented, Inheritable
• Change Look and Feel
• Cross-Platform

Imports

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

Class Structure

public class MainWindow extends JFrame 
                        implements ActionListener {

    public MainWindow() {
        // create GUI
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        // handle events
    }

    public static void main(String[] args){
        // start program
    }
}

Layout

// sets the size of this window
this.setSize(new Dimension(200, 100));

// tell the program to exit when this window is closed
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

// set the layout manager
this.setLayout(new GridBagLayout());

// Create the constraints for the GridBagLayout manager
GridBagConstraints gbc = new GridBagConstraints();

GridBagLayout

Image Credit: Oracle

GridBagLayout

Uses Rows & Columns

Image Credit: Oracle

GridBagLayout

Can Grow to Fit Screen

Image Credit: Oracle

Label

// set the constraints for the label
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.gridx = 0;
gbc.gridy = 0;

// add a label
this.add(new JLabel("Hello World!"), gbc);

Button

// reset the constraints for the button
gbc.gridx = 0;
gbc.gridy = 1;

// create a button 
JButton button = new JButton("Close");
// set the button's command:
button.setActionCommand("close");
// send the clicked event to this object
button.addActionListener(this);
// add the button
this.add(button, gbc);

Java Example

Handle Events

Specified by ActionListener interface

@Override
public void actionPerformed(ActionEvent e) {
    if ("close".equals(e.getActionCommand())) {
        // close button was clicked, so exit the application
        System.exit(0);
    }
}

Start Application

Use a Thread!

public static void main(String[] args){
    SwingUtilities.invokeLater(new Runnable() {
        public void run() {
            new MainWindow().setVisible(true);
        }
    });
}