Beginners Lab Java

:/*
*/
import java.applet.*;
import java.awt.*;
public class screencircle2 extends Applet implements Runnable
{
Thread t;
int i,j,k,l,flag=0,m,x1,y1,x2,y2,m1,x3,y3,m2,m3;
Color bg;
public void init()
{
}
public void start()
{
t=new Thread(this,"a");
t.start();
}
public void run()
{
paint1();
}
public void paint1()
{
Graphics g=getGraphics();
try
{
for(i=0;i<260;i++)
{
for(j=130;j<=260;j++)
{
g.setColor(Color.red);
g.fillOval(i,j,40,40);
Thread.sleep(50);
i=i+5;
j=j+5;
paint2();
if(j>=260)
{
k=i;
l=j;
paint3();
break;
}
}
}
}
catch(InterruptedException s)
{
//ShowStatus("error");
}
}
public void paint3()
{
setBackground(Color.black);
Graphics h=getGraphics();
try
{
for(x1=k;x1<=260;x1++)
{
for(y1=j;y1>1;y1--)
{
h.setColor(Color.red);
h.fillOval(x1,y1,40,40);
Thread.sleep(50);
x1=x1+6;
y1=y1-4;
paint2();
if(x1>=260)
{
m=x1;
m1=y1;
paint4();
}
}
}
}
catch(InterruptedException s1)
{
//ShowStatus("error");
}
}
public void paint4()
{
Graphics h1=getGraphics();
try
{
for(x2=m;x2>=40;x2--)
{
for(y2=m1;y2>=1;y1--)
{
h1.setColor(Color.red);
h1.fillOval(x2,y2,40,40);
Thread.sleep(50);
x2=x2-5;
y2=y2-6;
paint2();
if(y2<=1)
{
m2=x2;
m3=y2;
paint5();
}
}
}
}
catch(InterruptedException s1)
{
//ShowStatus("error");
}
}
public void paint5()
{
setBackground(Color.black);
Graphics h2=getGraphics();
try
{
for(x3=m2;x3>=1;x3--)
{
for(y3=m3;y3<260;y3++)
{
h2.setColor(Color.red);
h2.fillOval(x3,y3,40,40);
Thread.sleep(50);
x3=x3-6;
y3=y3+4;
paint2();
if(x3<=1)
{
m=x1;
m1=y1;
paint1();
}
}
}
}
catch(InterruptedException s1)
{
//ShowStatus("error");
}
}
public void paint2()
{
Graphics d=getGraphics();
d.setColor(Color.white);
d.fillRect(0,0,300,300);
setBackground(Color.black);
}
}