辅导program程序、讲解Java语言编程、Java程序设计调试

A GUI guide for Blackjack Project
GUI is short for Graphical User Interfaces. User can use GUI to communicate with program. In
java, we can use Swing or JavaFX to build a GUI. In this guide, we use Swing as an example.
1 Swing component
JFrame: Java GUI programs are based on JFrame. It is the object of the window on the screen,
which can be maximized, minimized and closed.
JPanel: The panel container class in swing. It is a lightweight Container, can be added to the
JFrame form. The function is to combine components with the same logic function in the
form.
JTextField: A lightweight component. It allow the user to edit single line text.
JButton: An instance of JButton class. Use to create buttons.
2 Hello world GUI
Code
import javax.swing.JFrame;
import javax.swing.JLabel;
import java.awt.*;
public class HelloWorld extends JFrame{
public HelloWorld(){
setTitle("Hello GUI");
// Set the window size
setSize(400,200);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Add a label
JLabel label = new JLabel("Hello world, this is my first swing GUI.");
Container container = getContentPane();
container.add(label);
setVisible(true);
}
public static void main(String[] args) {
new HelloWorld();
}
}
What you got
After clicking the button for 5 times,
3 More complex demo
Let's see a more complex demo with image.
Code
import javax.swing.*;
import java.awt.*;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
public class ComplexDemo extends JFrame {
public static void main(String args[]) {
JFrame frame = new JFrame("Complex demo");
JPanel panel = new JPanel();
frame.getContentPane();
JLabel label = new JLabel();
// The parameter should be the absolute path of the image file
ImageIcon img = new ImageIcon("");
img.setImage(img.getImage().getScaledInstance(200,300,
Image.SCALE_DEFAULT));
// Add the image as the content of the label
label.setIcon(img);
label.addMouseListener(new MouseListener() {
private int click_time = 0;
@Override
public void mouseClicked(MouseEvent e) {
// When mouse click the image
click_time ++;
String msg = String.format("You choose Hearts three. You
clicked %d time(s).", click_time);
JOptionPane.showMessageDialog(null, msg, "Message",
JOptionPane.INFORMATION_MESSAGE);
}
@Override
public void mousePressed(MouseEvent e) {
// You can write the action when the mouse pressed on the image
// Leave blank if you don't want to use it
}
@Override
public void mouseReleased(MouseEvent e) {
// You can write the action when the mouse released from the
image
// Leave blank if you don't want to use it
}
@Override
public void mouseEntered(MouseEvent e) {
// You can write the action when the mouse enter the image
// Leave blank if you don't want to use it
}
@Override
public void mouseExited(MouseEvent e) {
// You can write the action when the mouse exit from the image
// Leave blank if you don't want to use it
}
What you got
After clicking the image for three times,
});
panel.add(label);
panel.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
frame.add(panel);
frame.setSize(800, 600);
frame.setVisible(true);
}
}
Good luck and have fun!