Java 实例 使用递归来反转字符串

我们将看到两个程序来反转一个字符串。第一个程序使用递归反转给定的字符串，第二个程序读取用户输入的字符串然后反转它。

示例 1：用于反转字符串的程序

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);
    }
}

输出：

The reversed string is: koobsrennigeB ot emocleW

示例 2：用于反转用户输入的字符串的程序

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);
    }
}

输出：

Enter your username: 
How are you doing?
The reversed string is: ?gniod uoy era woH