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");
    }
}

}