Stuff

import java.awt.*;
import javax.swing.*;

public class Zoga{
	public static void main(String[] args){

		Toolkit tk = Toolkit.getDefaultToolkit();
		Dimension d = tk.getScreenSize();
		
		
		JFrame okno = new JFrame();
		okno.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		
        Vsebina vsebinaOkna = new Vsebina();
        vsebinaOkna.setBackground(new Color(255, 255, 255));
        vsebinaOkna.setPreferredSize(new Dimension(d.width, d.height));
		
		okno.getContentPane().add(vsebinaOkna, BorderLayout.CENTER);
		okno.pack();
		okno.setVisible(true);
		
		Animacija lolz = new Animacija();
		lolz.run(vsebinaOkna);
	}
}

class Vsebina extends JPanel{
	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	
	public int iks=0;
	public boolean naprej=true;
	public Toolkit tk = Toolkit.getDefaultToolkit();
	public Dimension d = tk.getScreenSize();
	
	public void paintComponent(Graphics g){
		super.paintComponent(g);
		g.setColor(Color.yellow);
		g.fillArc(iks,d.height/2,30,30,30,300);
	}
}

class Animacija extends Thread {
	public void run(Vsebina panel) {
		
		while(true) {
			
			if (panel.iks==0)
				panel.naprej=true;
			if (panel.iks==panel.d.width)
				panel.naprej=false;
			
			if(panel.naprej)
				panel.iks++;
			else
				panel.iks--;
			panel.d=panel.tk.getScreenSize();
			panel.repaint();
			try {
				Thread.sleep(1);
			} catch (InterruptedException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}	
	}
}