In this article, we will write a recursive Java function reverse(String s) that returns the string s in reverse.

package com.topjavatutorial.app;

import java.util.Scanner;

public class StringReverse {

  public static void main(String[] args) {

    System.out.println("Enter a String: ");
    Scanner sc = new Scanner(System.in);
    String str = sc.next();
    sc.close();
    System.out.printf("Reverse of %s is %s", str, reverse(str));
  }

  public static String reverse(String str) {

    if ((null == str) || (str.length() <= 1)) {
      return str;
    }
    // recursively add first char at end and reverse rest of the string
    return reverse(str.substring(1)) + str.charAt(0);
  }

}

The function recursively adds the last character of the string to the end and reverses rest of the String.

So, this is what is does :

reverse(ello) + h
reverse(llo) + e
reverse(lo) + l
reverse(o) + l
 

Output :

Enter a String:
hello
Reverse of hello is olleh
 

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