Change Object Color on scheduled time

Question

I am trying to simulate an intersection , so far i've painted my intersection . Now i want to make the traffic light. The problem is that i can't make my circle to change it's color from green to red every X seconds. Please help me.

import java.awt.Color;

import javax.jws.Oneway;
import javax.swing.JFrame;


public class Main {

    public static void main(String[] args) {
        MyMap map = new MyMap();
        JFrame f = new JFrame("Broadway Intersection");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        map.setBackground(Color.white);
        f.add(map);
        f.setSize(1366,738);
        f.setVisible(true);
    }

}


My Map class

import java.awt.Color;
import java.awt.Graphics;
import java.util.Timer;
import java.util.TimerTask;

import javax.swing.JPanel;

public class MyMap extends JPanel {
    public void paintComponent(final Graphics g) {
        super.paintComponent(g);

        g.setColor(Color.GREEN);
        g.fillRect(0, 0, 500, 250); // stanga sus
        g.fillRect(900, 0, 500, 250); // dreapta sus
        g.fillRect(0, 500, 500, 250);// stanga jos
        g.fillRect(900, 500, 500, 250); // dreapta jos

        g.setColor(Color.GRAY);
        g.fillRect(500, 0, 400, 900);
        g.fillRect(0, 250, 500, 250);
        g.fillRect(900, 250, 500, 250);

        g.setColor(Color.WHITE);
        g.fillRect(695, 0, 5, 100);// linii verticale
        g.fillRect(695, 150, 5, 100);
        g.fillRect(695, 500, 5, 100);
        g.fillRect(695, 650, 5, 50);

        g.fillRect(0, 370, 50, 5);
        g.fillRect(100, 370, 100, 5); // linii orizontale
        g.fillRect(250, 370, 100, 5);
        g.fillRect(400, 370, 100, 5);
        g.fillRect(900, 370, 100, 5);
        g.fillRect(1050, 370, 100, 5);
        g.fillRect(1200, 370, 100, 5);

        Timer timer = new Timer();
        boolean semaphore =true;
            timer.schedule(new TimerTask() {
                @Override
                public void run() {

                    g.setColor(Color.RED);
                    g.fillOval(700, 400, 20, 20);
                    System.out.println("tic tac");
                }
            }, 0, 5000);
            g.setColor(Color.GREEN);
            g.fillOval(700, 400, 20, 20);
    }

}

I have a circle in center that i want to change it's color , than i will start drawing my traffic light :D Thanks for everyone who is helping.

Answer 1

Try putting the Timer outside of your paintComponent() and have a Color object as a class member so it can be accessed in the Timer and paintComponent. When the timer reaches it's mark, It changes the color, then calls repaint. Try something like this (not tested)

import java.awt.Color;
import java.awt.Graphics;
import java.util.Timer;
import java.util.TimerTask;

import javax.swing.JPanel;

public class MyMap extends JPanel {

    Color color = Color.GREEN;     <-- class member

    public MyMap(){
        Timer timer = new Timer();
        boolean semaphore =true;    <-- not sure what this is for so I left it
        timer.schedule(new TimerTask() {
            @Override
            public void run() {
                color = Color.RED;      <-- change color

                repaint();              <-- repaint();

                System.out.println("tic tac");
            }
        }, 0, 5000);
    }

    public void paintComponent(final Graphics g) {
        super.paintComponent(g);

        g.setColor(Color.GREEN);
        g.fillRect(0, 0, 500, 250); // stanga sus
        g.fillRect(900, 0, 500, 250); // dreapta sus
        g.fillRect(0, 500, 500, 250);// stanga jos
        g.fillRect(900, 500, 500, 250); // dreapta jos

        g.setColor(Color.GRAY);
        g.fillRect(500, 0, 400, 900);
        g.fillRect(0, 250, 500, 250);
        g.fillRect(900, 250, 500, 250);

        g.setColor(Color.WHITE);
        g.fillRect(695, 0, 5, 100);// linii verticale
        g.fillRect(695, 150, 5, 100);
        g.fillRect(695, 500, 5, 100);
        g.fillRect(695, 650, 5, 50);

        g.fillRect(0, 370, 50, 5);
        g.fillRect(100, 370, 100, 5); // linii orizontale
        g.fillRect(250, 370, 100, 5);
        g.fillRect(400, 370, 100, 5);
        g.fillRect(900, 370, 100, 5);
        g.fillRect(1050, 370, 100, 5);
        g.fillRect(1200, 370, 100, 5);


        g.setColor(color);             <--- just use your color variable
        g.fillOval(700, 400, 20, 20);

    }
}

Edit: Try using a Swing Timer instead of the java.util.Timer

Timer timer = new Timer(5000, new ActionListener(){
    public void actionPerformed(ActionEvent e){
        color = Color.GREEN;
        repaint();
    }
});
timer.setRepeats(false);
timer.start();

Edit 2: keep alternating

Timer timer = new Timer(5000, new ActionListener(){
    public void actionPerformed(ActionEvent e){
        if (color.equals(Color.GREEN){
            color = Color.RED;
        } else {
            color = Color.GREEN;
        }
        repaint();
    }
});
timer.start();

Edit 3: Different time delays

Color color = Color.GREEN;
Timer timer;
public MyMap() {

    timer = null;
    timer = new Timer(5000, new ActionListener(){
        public void actionPerformed(ActionEvent e) {
            if (color.equals(Color.GREEN)) {
                color = Color.RED;
                timer.setDelay(2000);
            } else {
                color = Color.GREEN;
                timer.setDelay(8000);
            }
            repaint();
        }
    });
    timer.start();
}