# Java 程序：使用遞歸來反轉字符串 > 原文： [https://beginnersbook.com/2017/09/java-program-to-reverse-a-string-using-recursion/](https://beginnersbook.com/2017/09/java-program-to-reverse-a-string-using-recursion/) 我們將看到兩個程序來反轉一個字符串。第一個程序使用遞歸反轉給定的字符串，第二個程序讀取用戶輸入的字符串然后反轉它。 要了解這些程序，你應該具備以下[核心 java](https://beginnersbook.com/java-tutorial-for-beginners-with-examples/) 概念的知識： 1）[`substring()`](https://beginnersbook.com/2013/12/java-string-substring-method-example/) 2）[`charAt()`方法](https://beginnersbook.com/2013/12/java-string-charat-method-example/) ## 示例 1：用于反轉字符串的程序 ```java public class JavaExample { public static void main(String[] args) { String str = "Welcome to Beginnersbook"; String reversed = reverseString(str); System.out.println("The reversed string is: " + reversed); } public static String reverseString(String str) { if (str.isEmpty()) return str; //Calling Function Recursively return reverseString(str.substring(1)) + str.charAt(0); } } ``` **輸出：** ```java The reversed string is: koobsrennigeB ot emocleW ``` ## 示例 2：用于反轉用戶輸入的字符串的程序 ```java import java.util.Scanner; public class JavaExample { public static void main(String[] args) { String str; System.out.println("Enter your username: "); Scanner scanner = new Scanner(System.in); str = scanner.nextLine(); scanner.close(); String reversed = reverseString(str); System.out.println("The reversed string is: " + reversed); } public static String reverseString(String str) { if (str.isEmpty()) return str; //Calling Function Recursively return reverseString(str.substring(1)) + str.charAt(0); } } ``` **輸出：** ```java Enter your username: How are you doing? The reversed string is: ?gniod uoy era woH ```