Max Lab

Focus on backend, big data, and AI.

dev

Java Basics - Java GUI

/wrote/note-bak/dev/java/gui/

Java GUI

Desktop GUI applications

  • AWT(Abstract Window Toolkit)
  • Swing(Java Foundation Classes)
  • Pluggable Look and Feel
  • Platform Independent components
  • Enhanced component library

Swing v.s. AWT

  • AWT is a Java interface to native system GUI code present in your OS. It will not work the same on every system, although it tries.
  • Swing is a more-or-less pure-Java GUI. It uses AWT to create an operating system window and then paints everything else on it.
  • Thus Swing is 100% portable and is the same across platforms.

AWT Packages

  • java.awt
  • GUI container classes
  • Frame
  • Panel
  • Dialog
  • ScrollPane
  • GUI component classes
  • Button
  • TextField
  • Label
  • Layout managers
  • BorderLayout (Positions), default for Frame
  • FlowLayout (Alignments), default for Panel / Applet
  • GridLayout
  • CardLayout, add panels/cards one behind the other
  • NullLayout, custom
  • Custom graphics classes
  • Graphics
  • Color
  • Font
  • java.awt.event
  • Event classes
  • ActionEvent
  • MouseEvent
  • KeyEvent
  • WindowEvent
  • Event listener interfaces
  • ActionListener
  • MouseListener
  • KeyListener
  • WindowListener
  • Event listener adapter classes
  • MouseAdapter
  • KeyAdapter
  • WindowAdapter

Container

Top Lever Containers

  • Frame
  • Dialog
  • Applet Secondary Containers
  • Panel
  • ScrollPane

Frame

By default, frame’s size is (0,0) and visibility is false;

f = new Frame();
f.setSize(500, 500);
f.setVisible(true);

Event Handing

  • Component (source/listener object)
  • Button
  • Label
  • List
  • Checkbox
  • Choice
  • TextField
  • Event
  • Listener Work Flow
  • create Source Object (e.g. create a button)
  • create Listener Object (e.g. implement listener interface, override actionperformed method)
  • register Listener to Source (e.g. button.addActionListener(l))
  • wait for user to trigger the ActionListener -> (e.g. button create a new Event and invoke the actionperformend mehtod of the Lister Object) java_awt_flow.png notice: Listener interfaces are abstract, must override all methods; to avoid using interface, we can use(extends) the adapter (class)

Example

code source from https://www3.ntu.edu.sg/home/ehchua/programming/java/J4a_GUI.html

import java.awt.*; // Using AWT layouts
import java.awt.event.*; // Using AWT event classes and listener interfaces
import javax.swing.*; // Using Swing components and containers

// A Swing GUI application inherits from top-level container javax.swing.JFrame
public class SwingCounter extends JFrame { // JFrame instead of Frame
 private JTextField tfCount; // Use Swing's JTextField instead of AWT's TextField
 private JButton btnCount; // Using Swing's JButton instead of AWT's Button
 private int count = 0;
 
 // Constructor to setup the GUI components and event handlers
 public SwingCounter () {
 // Retrieve the content-pane of the top-level container JFrame
 // All operations done on the content-pane
 Container cp = getContentPane();
 cp.setLayout(new FlowLayout());
 
 cp.add(new JLabel("Counter"));
 tfCount = new JTextField("0", 10);
 tfCount.setEditable(false);
 cp.add(tfCount);
 
 btnCount = new JButton("Count");
 cp.add(btnCount);
 
 btnCount.addActionListener(new ActionListener() {
         @Override
 public void actionPerformed(ActionEvent evt) {
 ++count;
 tfCount.setText(count + "");
 }
 });
 
 setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 setTitle("Swing Counter");
 setSize(300, 100);
 setVisible(true);
 }
 
 public static void main(String[] args) {
 // Run the GUI construction in the Event-Dispatching thread for thread-safety
 SwingUtilities.invokeLater(new Runnable() {
         @Override
 public void run() {
 new SwingCounter(); // Let the constructor do the job
 }
 });
 }
}
  • Java Programming Tutorial(GUI)