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);

    }
}

Try using a Swing Timer instead of the java.util.Timer 尝试使用Swing Timer而不是java.util.Timer

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

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();

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();
}