String Reverse in Java

package raja.JavaPages4all;

public class Exam {

/**
* @param args
*/
public static void main(String[] args)
{
Stringreverse();
}

private static void Stringreverse()
{
String str="Raja is a Good Boy";
String reverse=null;

/*
* String reverse using StringBuffer
*/
reverse=new StringBuffer(str).reverse().toString();
System.out.println("String reverse using StringBuffer ="+reverse);

/*
* String reverse using StringBuilder
*/
reverse=new StringBuilder(str).reverse().toString();
System.out.println("String reverse using StringBuilder ="+reverse);

/*
* String reverse Without using API
*/
reverse="";
for(int i=str.length()-1;i>=0;i--)
{
reverse+=str.charAt(i);
}
System.out.println("String reverse Without using API ="+reverse);

System.out.println("reverseRecursively ="+reverseRecursively(str));
}

public static String reverseRecursively(String str)
{
/*
* base case to handle one char string and empty string
*/
if (str.length() < 2)
{
return str;
}

String res=reverseRecursively(str.substring(1)) + str.charAt(0);
return res;
}
}