Create TrafficLight.java

A program to simulate the red, yellow and green lights in a traffic signal using Java Swing.

Author: ShreyasAnish

AWT/TrafficLight.java

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+import java.awt.*;
+import javax.swing.*;
+import java.awt.event.*;
+
+class Signal extends JPanel{
+	Color on;
+	boolean change;
+	Signal(Color color){
+		on=color;
+		change=false;
+	}
+	public void turnOn(boolean a){
+		change=a;
+		repaint();
+	}
+	public Dimension getPreferredSize(){
+		int size=(50)*2;
+		return new Dimension(size,size);
+	}
+	public void paintComponent(Graphics g){
+		g.setColor(Color.black);
+		g.fillRect(0,0,150,250);
+		if(change){
+			g.setColor(on);
+		}
+		else{
+			g.setColor(Color.white);
+		}
+		g.fillOval(10,10,80,80);
+	}
+}
+
+public class TrafficLight extends JFrame implements ActionListener{
+	JRadioButton buttonRed,buttonYellow,buttonGreen;
+	Signal green=new Signal(Color.green);
+	Signal yellow=new Signal(Color.yellow);
+	Signal red=new Signal(Color.red);
+	
+	public TrafficLight(){
+		setLayout(new FlowLayout());
+		buttonRed=new JRadioButton("Red");
+		buttonYellow=new JRadioButton("Yellow");
+		buttonGreen=new JRadioButton("Green");
+		buttonRed.addActionListener(this);
+		buttonYellow.addActionListener(this);
+		buttonGreen.addActionListener(this);
+		JPanel trafficPanel=new JPanel(new GridLayout(3,1));
+		trafficPanel.add(red);
+		trafficPanel.add(yellow);
+		trafficPanel.add(green);
+		JPanel lightPanel=new JPanel(new FlowLayout());
+		lightPanel.add(buttonRed);
+		lightPanel.add(buttonYellow);
+		lightPanel.add(buttonGreen);
+		add(trafficPanel);
+		add(lightPanel);
+		pack();
+		setVisible(true);
+		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+	}
+	
+	public static void main(String args[]){
+		new TrafficLight();	
+	}
+
+	public void actionPerformed(ActionEvent e){
+		if(e.getSource()==buttonRed){
+			green.turnOn(false);
+			yellow.turnOn(false);
+			red.turnOn(true);
+			buttonYellow.setSelected(false);
+			buttonGreen.setSelected(false);
+		}
+		else if(e.getSource()==buttonYellow){
+			green.turnOn(false);
+			yellow.turnOn(true);
+			red.turnOn(false);
+			buttonRed.setSelected(false);
+			buttonGreen.setSelected(false);
+		}
+		else if(e.getSource()==buttonGreen){
+			green.turnOn(true);
+			yellow.turnOn(false);
+			red.turnOn(false);
+			buttonYellow.setSelected(false);
+			buttonRed.setSelected(false);
+		}
+	}
+}