Question

我的程序需要从用户读取一个字符串和两个索引值，然后用指定的索引值交换字符，并将结果字符串保存在变量中。现在我所能做的就是交换用户输入字符串的2个首字母，我无法弄清楚如何从用户交换2个索引值

Answer 1

使用String.toCharArray()将输入转换为char[]。然后，您可以使用索引并交换所需的字符。然后，您只需要从数组中构造一个新字符串。请参阅String javadocs。

Answer 2

如果您拥有原始String和两个索引，则可以交换这样的字符。

public static String swapChars(String word, int firstIndex, int secondIndex) {
    if (Math.min(firstIndex, secondIndex) < 0 || Math.max(firstIndex, secondIndex) > word.length() - 1) { // If either of the indices are negative or too large, throw an exception
        throw new IllegalArgumentException("Indices out of bounds!");
    }
    if (firstIndex == secondIndex) { // If they are equal we can return the original string/word
        return word;
    }
    char[] characters = word.toCharArray(); // Make a char array from the string
    char first = characters[firstIndex]; // Store the character at the first index
    characters[firstIndex] = characters[secondIndex]; // Change the character at the first index
    characters[secondIndex] = first;  // Change the character at the second index using the stored character
    return new String(characters); // Return a newly built string with the char array
}

读取一个字符串和两个索引变量，然后交换指定索引中的那些字符

2 个答案: