Java中如何将字符串后半部分的h与t互相替换？

要实现字符串后半部分的'h'和't'互换，你需要针对每个字符做判断替换，而非单纯交换字符位置。以下是几种可行的实现方式：

方法一：遍历字符数组逐个替换 #

这是最直观的实现方式，将后半部分转为字符数组后，遍历每个元素完成替换：

public class Tollring3 {
    public static void main(String args[]) {
        String base = "httthhhtth";
        int half = base.length() / 2;
        String first = base.substring(0, half);
        String second = base.substring(half);
        
        System.out.println("Actual String :- " + base);
        System.out.println("First half: " + first);
        System.out.println("Original second half: " + second);
        
        // 将后半部分转为字符数组
        char[] c = second.toCharArray();
        // 遍历每个字符，替换h和t
        for (int i = 0; i < c.length; i++) {
            if (c[i] == 'h') {
                c[i] = 't';
            } else if (c[i] == 't') {
                c[i] = 'h';
            }
            // 其他字符保持不变（如果存在）
        }
        
        String swappedString = new String(c);
        System.out.println("Swapped second half: " + swappedString);
        // 拼接前后两部分得到最终字符串
        String result = first + swappedString;
        System.out.println("Final result: " + result);
    }
}

方法二：字符串替换技巧（仅适用于h和t互换场景） #

利用字符串的replace方法，注意替换顺序避免覆盖冲突：先把'h'替换为临时字符，再替换't'为'h'，最后把临时字符转为't'：

public class Tollring3 {
    public static void main(String args[]) {
        String base = "httthhhtth";
        int half = base.length() / 2;
        String first = base.substring(0, half);
        String second = base.substring(half);
        
        System.out.println("Actual String :- " + base);
        System.out.println("First half: " + first);
        System.out.println("Original second half: " + second);
        
        // 按顺序替换h和t，避免互相覆盖
        String swappedString = second.replace('h', '#')
                                     .replace('t', 'h')
                                     .replace('#', 't');
        
        System.out.println("Swapped second half: " + swappedString);
        String result = first + swappedString;
        System.out.println("Final result: " + result);
    }
}

方法三：Java 8+ Stream API（简洁写法） #

通过流处理每个字符，完成替换后拼接成字符串：

import java.util.stream.Collectors;

public class Tollring3 {
    public static void main(String args[]) {
        String base = "httthhhtth";
        int half = base.length() / 2;
        String first = base.substring(0, half);
        String second = base.substring(half);
        
        System.out.println("Actual String :- " + base);
        System.out.println("First half: " + first);
        System.out.println("Original second half: " + second);
        
        String swappedString = second.chars()
                                     .mapToObj(c -> (char) c)
                                     .map(ch -> ch == 'h' ? 't' : (ch == 't' ? 'h' : ch))
                                     .map(String::valueOf)
                                     .collect(Collectors.joining());
        
        System.out.println("Swapped second half: " + swappedString);
        String result = first + swappedString;
        System.out.println("Final result: " + result);
    }
}

输出结果 #

以上三种方法运行后都会得到：

Actual String :- httthhhtth
First half: httth
Original second half: hhtth
Swapped second half: ttthh
Final result: httthttthh

内容的提问来源于stack exchange，提问作者Ravi Ranjan