讀取一個字符串和2個索引變量，然後交換指定索引中的那些字符

Question

我的程序需要從用戶讀取一個字符串和兩個索引值，然後將字符與指定索引值交換，並將結果字符串保存在變量中。 現在我所能做的就是交換用戶輸入字符串的2個字母，我無法弄清楚如何從用戶

Answer 1

使用String.toCharArray()交換2個索引值的輸入轉換爲char[]。然後，您可以使用索引並交換所需的字符。然後你需要的是從數組中構造一個新的字符串。請參閱String javadocs。

Answer 2

假設您有原始的String和兩個索引，您可以像這樣交換字符。

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 
}