Java如何交换字符串中两个位置的值

public static void main(String[] args) {
    String str = "abcd";
    int i = 0, j = 2;
    char[] strArray = str.toCharArray(); // 转换成数组
    char temp = strArray[i];
    strArray[i] = strArray[j];
    strArray[j] = temp;
    str = String.valueOf(strArray);
    System.out.println(str);
}

public class TestReverse {
    public static void main(String[] args) {
        String str = "abcde";
        System.out.println(replaceBeginAndEnd(str, 2));
    }
    public static String replaceBeginAndEnd(String str, int i) {
        if (str == null || i < 0 || str.length() <= i) {
            return str;
        }
        char[] chars = str.toCharArray();
        reverseCharArray(chars, 0, i - 1);
        reverseCharArray(chars, i + 1, chars.length - 1);
        reverseCharArray(chars, 0, chars.length - 1);
        return new String(chars);
    }
    private static void reverseCharArray(char[] chars, int begin, int end) {
        char temp;
        while (begin < end) {
            temp = chars[begin];
            chars[begin] = chars[end];
            chars[end] = temp;
            begin++;
            end--;
        }
    }
}