反转字符串

使用StringBuilder或StringBuffer：

• StringBuilder 和 StringBuffer 类都有 reverse 方法，可以方便地反转字符串。

public class ReverseString {
    public static void main(String[] args) {
        String original = "Hello, World!";
        
        // 使用StringBuilder
        StringBuilder reversedBuilder = new StringBuilder(original).reverse();
        String reversedStringBuilder = reversedBuilder.toString();
        System.out.println("Reversed with StringBuilder: " + reversedStringBuilder);

        // 使用StringBuffer
        StringBuffer reversedBuffer = new StringBuffer(original).reverse();
        String reversedStringBuffer = reversedBuffer.toString();
        System.out.println("Reversed with StringBuffer: " + reversedStringBuffer);
    }
}

使用toCharArray和数组操作：

• 将字符串转换为字符数组，然后使用数组操作进行反转。

public class ReverseString {
    public static void main(String[] args) {
        String original = "Hello, World!";
        
        // 使用toCharArray和数组操作
        char[] charArray = original.toCharArray();
        int left = 0;
        int right = charArray.length - 1;

        while (left < right) {
            // 交换字符
            char temp = charArray[left];
            charArray[left] = charArray[right];
            charArray[right] = temp;

            // 移动指针
            left++;
            right--;
        }

        String reversedCharArray = new String(charArray);
        System.out.println("Reversed with charArray: " + reversedCharArray);
    }
}

使用递归：

• 通过递归来反转字符串。

public class ReverseString {
    public static void main(String[] args) {
        String original = "Hello, World!";
        
        // 使用递归
        String reversedRecursive = reverseRecursive(original);
        System.out.println("Reversed with recursion: " + reversedRecursive);
    }

    private static String reverseRecursive(String str) {
        if (str.isEmpty()) {
            return str;
        } else {
            return reverseRecursive(str.substring(1)) + str.charAt(0);
        }
    }
}