I'm trying to create a simulator that will print what color a traffic light is currently at into a JTextField when the "start" button is clicked. However, clicking the button doesn't do anything. I have System.out lines that work with the same operation, but the text field won't change. I even tried putting in a custom String just to see if it'll change on the button click, but it doesn't, and I'm not really sure why it's doing this.
This is the action listener for the button
start.addActionListener((ActionEvent e) -> {
//String x = "hello";
//firstLight.setText(x);
TrafficLightSimulator tl =
new TrafficLightSimulator(TrafficLightColor.GREEN, "Thread 1");
TrafficLightSimulator t2 =
new TrafficLightSimulator(TrafficLightColor.RED, "Thread 2");
TrafficLightSimulator t3 =
new TrafficLightSimulator(TrafficLightColor.YELLOW, "Thread 3");
Thread thrd = new Thread(tl);
thrd.setName("Thread 1");
Thread thrd2 = new Thread(t2);
thrd.setName("Thread 2");
Thread thrd3 = new Thread(t3);
thrd.setName("Thread 3");
thrd.start();
thrd2.start();
thrd3.start();
firstLight.setText("hello");
for(int i=0; i < 9; i++) {
firstLight.setText("hello");
secondLight.setText(tl.getColor().toString());
System.out.println(tl.name + " is at " + tl.getColor());
System.out.println(t2.name + " is at " + t2.getColor());
System.out.println(t3.name + " is at " + t3.getColor());
tl.waitForChange();
t2.waitForChange();
t3.waitForChange();
}
tl.cancel();
t2.cancel();
t3.cancel();
});
And this is the whole code
/*
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*/
package intersectionsimulator;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.*;
import java.awt.event.ActionEvent;
import javax.swing.*;
public class IntersectionSimulator extends JFrame {
private JFrame frame;
private JPanel buttonPanel;
private JPanel outputPanel;
private JButton pause;
private JButton start;
private JButton stop;
private JLabel light1;
private JLabel light2;
private JLabel light3;
private JLabel car1;
private JLabel car2;
private JLabel car3;
private JTextField firstLight;
private JTextField secondLight;
private JTextField thirdLight;
private JTextField firstCar;
private JTextField secondCar;
private JTextField thirdCar;
IntersectionSimulator() {
frame = new JFrame("Intersection Simulator");
frame.setSize(750,500);
frame.setLayout(new GridLayout(1,2));
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
buttonPanel = new JPanel();
outputPanel = new JPanel();
pause = new JButton("Pause");
start = new JButton("Start");
stop = new JButton("Stop");
light1 = new JLabel("First Traffic Light");
light2 = new JLabel("Second Traffic Light");
light3 = new JLabel("Third Traffic Light");
car1 = new JLabel("First Car");
car2 = new JLabel("Second Car");
car3 = new JLabel("Third Car");
firstLight = new JTextField(50);
secondLight = new JTextField(50);
thirdLight = new JTextField(50);
firstCar = new JTextField(50);
secondCar = new JTextField(50);
thirdCar = new JTextField(50);
buttonPanel.setLayout(new GridLayout(3,1));
buttonPanel.add(start);
buttonPanel.add(pause);
buttonPanel.add(stop);
frame.add(buttonPanel);
outputPanel.setLayout(new GridLayout(6,2));
outputPanel.add(light1);
outputPanel.add(firstLight);
outputPanel.add(light2);
outputPanel.add(secondLight);
outputPanel.add(light3);
outputPanel.add(thirdLight);
outputPanel.add(car1);
outputPanel.add(firstCar);
outputPanel.add(car2);
outputPanel.add(secondCar);
outputPanel.add(car3);
outputPanel.add(thirdCar);
frame.add(outputPanel);
frame.setVisible(true);
start.addActionListener((ActionEvent e) -> {
//String x = "hello";
//firstLight.setText(x);
TrafficLightSimulator tl =
new TrafficLightSimulator(TrafficLightColor.GREEN, "Thread 1");
TrafficLightSimulator t2 =
new TrafficLightSimulator(TrafficLightColor.RED, "Thread 2");
TrafficLightSimulator t3 =
new TrafficLightSimulator(TrafficLightColor.YELLOW, "Thread 3");
Thread thrd = new Thread(tl);
thrd.setName("Thread 1");
Thread thrd2 = new Thread(t2);
thrd.setName("Thread 2");
Thread thrd3 = new Thread(t3);
thrd.setName("Thread 3");
thrd.start();
thrd2.start();
thrd3.start();
firstLight.setText("hello");
for(int i=0; i < 9; i++) {
firstLight.setText("hello");
secondLight.setText(tl.getColor().toString());
System.out.println(tl.name + " is at " + tl.getColor());
System.out.println(t2.name + " is at " + t2.getColor());
System.out.println(t3.name + " is at " + t3.getColor());
tl.waitForChange();
t2.waitForChange();
t3.waitForChange();
}
tl.cancel();
t2.cancel();
t3.cancel();
});
}
enum TrafficLightColor {
RED, GREEN, YELLOW
}
class TrafficLightSimulator implements Runnable {
private TrafficLightColor tlc; // holds the current traffic light color
private boolean stop = false; // set to true to stop the simulation
private boolean changed = false; // true when the light has changed
String name;
TrafficLightSimulator(TrafficLightColor init, String n) {
tlc = init;
name = n;
}
TrafficLightSimulator() {
tlc = TrafficLightColor.RED;
}
// Start up the light.
@Override
public void run() {
while(!stop) {
try {
switch(tlc) {
case GREEN:
Thread.sleep(10000); // green for 10 seconds
break;
case YELLOW:
Thread.sleep(2000); // yellow for 2 seconds
break;
case RED:
Thread.sleep(12000); // red for 12 seconds
break;
}
} catch(InterruptedException exc) {
System.out.println(exc);
}
changeColor();
}
}
// Change color.
synchronized void changeColor() {
switch(tlc) {
case RED:
tlc = TrafficLightColor.GREEN;
break;
case YELLOW:
tlc = TrafficLightColor.RED;
break;
case GREEN:
tlc = TrafficLightColor.YELLOW;
}
changed = true;
notify(); // signal that the light has changed
}
// Wait until a light change occurs.
synchronized void waitForChange() {
try {
while(!changed)
wait(); // wait for light to change
changed = false;
} catch(InterruptedException exc) {
System.out.println(exc);
}
}
// Return current color.
synchronized TrafficLightColor getColor() {
return tlc;
}
// Stop the traffic light.
synchronized void cancel() {
stop = true;
}
}
public static void main(String[] args) {
IntersectionSimulator is = new IntersectionSimulator();
}
}
