Notes

/*
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/**
*
*/
import java.awt.*;
import java.awt.event.*;
import javax.swing.JFrame;
import javax.swing.Timer;

class PrimoTimer extends Panel implements ActionListener {
int conta = 0;
static int w=300;
static int h=150;
boolean x1 = true;
int x = 0;
int lato = 100; // lato del quadrato del fotogramma
int millisec;
Timer timer;

public PrimoTimer(int ritardo) {
millisec = ritardo;
timer = new Timer(millisec, this);
timer.start();
}

public void actionPerformed(ActionEvent e) {
conta++;
repaint();
}

public void paint(Graphics g) {
super.paint(g);
g.setColor(Color.black);
g.fillOval(0+x, (h-60)/2, 30, 30);
g.setColor(Color.white);
if (x1)
x++;
else
x--;
if (x==w-35)
x1=false;
else
if (x==0)
x1=true;

}

public static void main(String[] args) {
JFrame f = new JFrame("Conta col timer");
PrimoTimer pt = new PrimoTimer(30);
// colore di sfondo
f.setBackground(Color.blue);
f.add(pt);
// dimensiono il frame
f.setSize(new Dimension(w,h));
f.setVisible(true);
f.setResizable(false);
f.setLocationRelativeTo(null);
f.setDefaultOperation(EXIT_ON_CLOSE);
}
}