strings in java(18 june ,2011)

please explain me the flow of this program..not able to execute correctly n wats the use of clone

public class Strclone {

public static void main(String args[]) { String s=new String("a"); String s1 = "Hello"; System.out.println(s1.length()); String s2 = "Hello";

String s3 = new String(s1);

String s4 =(String) s2.clone();

Object c=s.clone();
String b;
if(s==b)
{
    System.out.println("true");

}
if(s.clone().equals(s))
{
    System.out.println("equals");
}

}

}