import java.awt.Color;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;

import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class Teste extends JFrame {

    JPanel jp;

    int dx = 175, dy = 125; //posicoes
    int vx, vy; //velocidades

    public Teste() {

        super("Joguinho");

        Container c = getContentPane();
        c.setLayout(new FlowLayout());
        jp = new JPanel();
        jp.setBackground(Color.black);
        jp.setBorder(BorderFactory.createLineBorder(Color.BLUE, 5));
        jp.setPreferredSize(new Dimension(380, 250));
        c.add(jp);

        new Update().start();
        setSize(400, 300);
        setLocationRelativeTo(null);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
    }

    @Override
    public void paint(Graphics g) {

        super.paint(g);
        g.setColor(Color.RED);
        g.fillOval(dx, dy, 50, 50);
    }
    private void verificaColisao() {
        if(dx < 0) {
            System.out.println("bateu");
        }

    }

    public class Update extends Thread {

        @Override
        public void run() {
            while(true) {

                try {
                    Thread.sleep(400);
                    dx -= 20;
                    verificaColisao();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                    }
                repaint();
                }
        }
    }
    public static void main(String[] args) {

        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                new Teste().setVisible(true);

            }
        });
    }
}