Java Program to Reverse a Sentence Using Recursion
In this program, you’ll learn to reverse a given sentence using a recursive loop in Java.
Example: Reverse a Sentence Using Recursion
public class Reverse {public static void main(String[] args) {String sentence = "Go work";String reversed = reverse(sentence);System.out.println("The reversed sentence is: " + reversed);}public static String reverse(String sentence){if (sentence.isEmpty())return sentence;return reverse(sentence.substring(1)) + sentence.charAt(0);}}
When you run the program, the output will be:
The reversed sentence is: krow oG
In the above program, we’ve a recursive function reverse().
On each iteration, we add (concatenate) the result of next reverse() function to the first character of sentence using charAt(0).
The recursive call must be before the charAt(), because that way the last characters will start adding to the left hand side. If you reverse the order, you’ll end up with the original sentence.
In the end, we end up with an empty sentence and reverse() returns the reversed sentence.
| Iteration | reverse() | substring() | reversedString |
|---|---|---|---|
| 1 | reverse(“Go work”) | “o Work” | result + “G” |
| 2 | reverse(“o Work”) | ” Work” | result + “o” + “G” |
| 3 | reverse(” Work”) | “Work” | result + ” ” + “o” + “G” |
| 4 | reverse(“Work”) | “ork” | result + “W” + ” ” + “o” + “G” |
| 5 | reverse(“ork”) | “rk” | result + “o” + “W” + ” ” + “o” + “G” |
| 6 | reverse(“rk”) | “k” | result + “r” + “o” + “W” + ” ” + “o” + “G” |
| 7 | reverse(“k”) | “” | result + “k” + “r” + “o” + “W” + ” ” + “o” + “G” |
| Final | reverse(“”) | – | “” + “k” + “r” + “o” + “W” + ” ” + “o” + “G” = “kroW oG” |