while (running) {
  updateCars();
  repaint();
}

package traffic;
 
 
import java.awt.Color;
import java.awt.Graphics2D;
 
 
public class vehicle {
 
    private static final int size = 20;
    private Color vehicleColor;
    private int Xvehicle, Yvehicle, speedVehicle; 
 
    public vehicle(int x, int y, int velocity) {
 
        vehicleColor = Color.BLUE;  
        Xvehicle =  x;
        Yvehicle = y;
        speedVehicle = velocity;
 
 
     }
 
    public void drive() {
 
 
        Xvehicle += speedVehicle;
 
    }
 
 
    public void draw(Graphics2D g2) {
 
        g2.setColor(vehicleColor);
        g2.fillRect(Xvehicle, Yvehicle, size, size);
 
            }
 
 
}

package traffic;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.Timer;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
 
 
 
public class Anime extends junction  {
 
 
    private vehicle vec_1  = new vehicle(80,365, 2);
 
    private int   a_interval  =43;
    private int   b_interval = 7000;
    private Timer a_timer, b_timer;
 
 
    public Anime() {
 
        a_timer = new Timer(a_interval, new Timer1());
 
       b_timer = new Timer(b_interval, new Timer2());
    }
 
    public void setAnimation(boolean StartStop) {
        if (StartStop) {
            a_timer.start();
            b_timer.start();
        } else {
 
            a_timer.stop();
            b_timer.stop();
        }
    }
 
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
       Graphics2D g3 = (Graphics2D) g;
       vec_1.draw(g3);
 
 
 
    }
 
 
 
    class Timer1 implements ActionListener {
 
        public void actionPerformed(ActionEvent e) {
 
            vec_1.drive();
            repaint();
        }
    }
 
 
class Timer2 implements ActionListener {
 
        public void actionPerformed(ActionEvent e) {
             // g = (Graphics2D)this.getGraphics();
            //create new vehicle randomly...
        }
    }
}