String builder class : JAVA Programming by "Gopal Krishna"

public class bld
{
public static void main(String arg[])
{
 StringBuilder sb=new StringBuilder("hello");
 System.out.println(sb.append("hi"));
 System.out.println(sb.insert(2,"ram"));
 System.out.println(sb.replace(2,7,"ram"));
 System.out.println(sb.reverse());
 System.out.println(sb.delete(2,4));
}
}