class that reverses a long string efficiently with StringBuilder

ReverseLongerStr.java

import java.lang.StringBuilder;

public class ReverseLonger {

  public static String shorterReverseLonger(String a, String b) {
     if (a.length() < b.length()) {
        return a + reverse(b) + a;
     } else {
       return b + reverse(a) + b;
     }
  }

  public static String reverse(String str) {
    String reverse = new StringBuilder(str).reverse().toString();
    return reverse;
  }  
}