java - 如何在 Java 中交换字符数组(就地)

Question

所以基本上不能/允许创建一个新数组。除了实际更改和操作当前数组外，无法返回任何内容。您如何获取字符数组并简单地翻转/反转它们。

Starting array: ['P','e','r','f','e','c','t',' ','M','a','k','e','s',' ','P','r','a','c','t','i','c','e']

反转每个单词，用空格隔开

Reversed: ['P','r','a','c','t','i','c','e',' ','M','a','k','e','s',' ','P','e','r','f','e','c','t'] 

这是我目前的情况

代码:

  class Main {
     public static void main(String[] args) {
       char[] charArr = new char[] {'P','e','r','f','e','c','t',' ','M','a','k','e','s',' ','P','r','a','c','t','i','c','e'};
       reverseCharArray(charArr);
     }


     public static void reverseCharArray() {
       int arrLength = charArr.length;
       for (int i = 0; i <= arrLength / 2; i++) {
         charArr[arrLength - i - 1] = charArr[i];
         System.out.println(charArr);
       }
     }
   }

更新: 好的，我发现的是。我需要做的实际上是交换字符句子拼写的单词。使句子向后/颠倒。

注意:这是在此处的在线采访中尝试的: enter link description here

Answer 1

这绝对不是一个好的解决方案，但它是一个可行的解决方案。

class Main {

public static void main(String[] args) {
    char[] charArr = new char[] { 'P', 'e', 'r', 'f', 'e', 'c', 't', ' ', 'M', 'a', 'k', 'e', 's', ' ', 'P', 'r',
            'a', 'c', 't', 'i', 'c', 'e' };
    System.out.println(charArr);
    reverseCharArray(charArr,0);
    System.out.println(charArr);
}


public static void reverseCharArray(char[] charArr, int sorted) {


    /* Look for last space*/
    int lastSpace = -1;
    for (int i = 0; i < charArr.length; i++) { 
        if (charArr[i] == ' ') {
            lastSpace = i; 
        }
    }

    /* Grab the word and move it at the beginning of the sorted array */
    for (int i = lastSpace + 1; i < charArr.length; i++) {

        int k = i;

        while (k != sorted) {
            char tmp = charArr[k-1];
            charArr[k-1] = charArr[k];
            charArr[k] = tmp;
            k--;
        }

        sorted++;
    }


    /* At this point, the last character is a space*/
    /* Else, we've swapped all the words */
    int k = charArr.length - 1;
    if (charArr[k] != ' ') {
        return;
    }

    /* If it's a space, grab it and move it at the beginning*/
    while (k != sorted) {
        char tmp = charArr[k-1];
        charArr[k-1] = charArr[k];
        charArr[k] = tmp;
        k--;
    }
    sorted++;


    /*Recursive call on the not sorted array*/
    reverseCharArray(charArr,sorted);

}}