Implementing Traffic Signal Using Java Swing Components

Last Updated : 17 Sep, 2021

Create a Button Group such that it contains three radio buttons Red, Yellow, Green when red is clicked you want to display “Stop”, when orange is clicked you want to display “ready”, when the green button is clicked Display “Go” and also create a sample Traffic signal demo using rectangle and ovals using 2D graphics.

Implementation:

Example

Java

// Java Program to Implement Traffic signal
// Using Java Swing Components
 
// Importing required classes
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
 
// Main class
// Extending JFrame class and
// Implementing ItemListener interface
public class Traffic_Signal
    extends JFrame implements ItemListener {
 
    // Setting the buttons for the layout
    JRadioButton jr1;
    JRadioButton jr2;
    JRadioButton jr3;
 
    // Setting the field area
    JTextField j1 = new JTextField(10);
    ButtonGroup b = new ButtonGroup();
    String msg = " ";
 
    // Initially setting the co-ordinates to 0,0,0
    int x = 0, y = 0, z = 0;
    public Traffic_Signal(String msg)
    {
        super(msg);
        setLayout(new FlowLayout());
 
        // Assigning name to the button declared above
        // with help of JRadioButton class
        jr1 = new JRadioButton("Red");
        jr2 = new JRadioButton("Yellow");
        jr3 = new JRadioButton("Green");
 
        jr1.addItemListener(this);
        jr2.addItemListener(this);
        jr3.addItemListener(this);
 
        add(jr1);
        add(jr2);
        add(jr3);
        b.add(jr1);
        b.add(jr2);
        b.add(jr3);
        add(j1);
 
        // Method 1
        // To add a window
        addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e)
            {
                // It haults here itself
                System.exit(0);
            }
        });
    }
 
    // Method 2
    // To change colors of traffic signal
    public void itemStateChanged(ItemEvent ie)
    {
        // If it is red
        if (ie.getSource() == jr1) {
            if (ie.getStateChange() == 1) {
 
                // Then display message- Stop
                msg = "Stop!";
                x = 1;
 
                // Repainting the box with original one
                // Practically black
                repaint();
            }
            else {
                msg = "";
            }
        }
 
        // If state is Orange or technically jr2
        if (ie.getSource() == jr2) {
            if (ie.getStateChange() == 1) {
 
                // Then display message-
                // Get ready in waiting state
                msg = "Get Ready to go!";
                y = 1;
 
                // Again repainting the button
                repaint();
            }
            else {
                msg = "";
            }
        }
 
        // If state is Green
        if (ie.getSource() == jr3) {
            if (ie.getStateChange() == 1) {
 
                // Then display message- Go
                msg = "Go!!";
                z = 1;
                repaint();
            }
            else {
                msg = "";
            }
        }
        j1.setText(msg);
    }
 
    // Method 3
    // handling the paint graphics and
    // dimensions of the buttons via
    // setting co-ordinates
    public void paint(Graphics g)
    {
        g.drawRect(100, 105, 110, 270);
        g.drawOval(120, 150, 60, 60);
        g.drawOval(120, 230, 60, 60);
        g.drawOval(120, 300, 60, 60);
 
        // Case: Red
        if (x == 1) {
            g.setColor(Color.RED);
            g.fillOval(120, 150, 60, 60);
            g.setColor(Color.WHITE);
            g.fillOval(120, 230, 60, 60);
            g.setColor(Color.WHITE);
            g.fillOval(120, 300, 60, 60);
            x = 0;
        }
 
        // Case: Orange
        if (y == 1) {
            g.setColor(Color.WHITE);
            g.fillOval(120, 150, 60, 60);
            g.setColor(Color.YELLOW);
            g.fillOval(120, 230, 60, 60);
            g.setColor(Color.WHITE);
            g.fillOval(120, 300, 60, 60);
            y = 0;
        }
 
        // Case: Green
        if (z == 1) {
            g.setColor(Color.WHITE);
            g.fillOval(120, 150, 60, 60);
            g.setColor(Color.WHITE);
            g.fillOval(120, 230, 60, 60);
            g.setColor(Color.GREEN);
            g.fillOval(120, 300, 60, 60);
            z = 0;
        }
    }
 
    // Method 4
    // Main driver method
    public static void main(String args[])
    {
        // Creating object of Jframe class inside main()
        // method
        JFrame jf = new Traffic_Signal("Traffic Light");
 
        // Setting size and making traffic signal
        // operational using setVisible() method
        jf.setSize(500, 500);
        jf.setVisible(true);
    }
}