Question

我尝试创建一种方法，该方法接受字符串数组并返回单个格式化的字符串。最后一个单词应以单词“ and”（而不是逗号）分隔。

但是它没有按预期工作：）它不会用单词“和”代替最后一个逗号。您能告诉我我的错误在哪里吗？

谢谢。

public class Kata {
    public static String formatWords(String[] words) {
        List<String> words1 = Arrays.asList(words);
        ListIterator<String> wordIter = words1.listIterator();
        StringBuilder out = new StringBuilder();

        while (wordIter.hasNext()) {
            out.append(wordIter.next());

            if (wordIter.hasNext()) {
                out.append(",");
            }
        }

        return out.toString().replaceAll(",$", "and");
    }
}

Answer 1

我要迭代到前一个元素，然后用逗号将字符串连接起来，然后用“ and”将最后一个字符串连接起来：

public static String formatWords(String[] words) {
   // Handle nulls and empty arrays
   if (words == null || words.length) {
        return "";
    }

    // Handle the first word
    StringBuilder sb = new StringBuilder(words[0]);

    // Handle all the words from the second to the before last
    for (int i = 1; i < words.lengh - 1; ++i) {
        sb.append(", ").append(word[i]);
    }

    // Check that there are at least two words
    if (words.length > 1) {
        // Handle the last word with an "and"
        sb.append(" and ").append(words[1])
    }
}

Answer 2

replaceAll(",$", "and");并没有您的想法。它找不到字符串中的最后一个,。

尝试一下

while(wordIter.hasNext()) {
    //your code

}

if (words.length > 1) {
    int indexOfLastComma = out.length() - words[words.length - 1].length();
    return out.replace(indexOfLastComma - 1, indexOfLastComma, " and ").toString();
}
return out.toString();

我们找到最后一个逗号的索引，然后将其替换为and。

这是使用Streams的一种有趣方式

String tempResult = IntStream.range(0, words.length - 1)
        .mapToObj(i -> words[i])
        .collect(Collectors.joining(","));
return words.length > 1 ? tempResult + " and " + words[words.length - 1] : words[0];

编辑：

要过滤出空词，可以使用过滤器。现在，最后检查words.length > 1将不再起作用（因为它可以包含空字符串）。因此，我正在检查tempResult是否至少有一个,。

这是一个完整的解决方案

String tempResult = Arrays.stream(words)
       .filter(word -> !word.isEmpty())
       .collect(Collectors.joining(","));
int indexOfLastComma = tempResult.lastIndexOf(',');
return indexOfLastComma != -1 ? tempResult.substring(0, indexOfLastComma) + " and "
        + tempResult.substring(indexOfLastComma + 1): tempResult;

它创建子字符串-因此不是最有效的解决方案。

Answer 3

由于您可能有空项目，请先使用列表清除空项目：

public static String formatWords(String[] words) {
    if (words == null)
        return "";

    List<String> list = new ArrayList<>();

    for (String word : words) {
        word = word.trim();
        if (!word.isEmpty())
            list.add(word);
    }

    StringBuilder out = new StringBuilder();

    int len = list.size();

    for (int i = 0; i < len; i++) {
        out.append(list.get(i));
        if (i == len - 2)
            out.append(" and ");
        else if (i < len - 2)
            out.append(",");
    }

    return out.toString();
}

public static void main(String[] args) {
    String[] array = {"", "apples", "", "oranges", "", "melons", ""};
    System.out.println(formatWords(array));
}

将打印：

apples,oranges and melons

Answer 4

您不需要使用List和ListIterator（在这种情况下！）这是我的解决方案！

ps：我不明白为什么该方法是静态的，我认为在此Casa中是不必要的，因为我们不处理任何静态变量。

public static String formatWords(String[]words){

    //Usefull to build the final resoult
    StringBuilder sb = new StringBuilder(); 

    /*start to put the word in the string builder
    from the first to the last*/
    for (int i = 0; i < words.length; i++) {

        //put the wordat position i in string builder
        sb.append(words[i]);

        /*if the word is the 2 last and there are egual or more than 
        2 elements in words array
        we can add the "and"*/
        if(i==words.length-2 && words.length>=2) { 
            sb.append(" and "); 

         /*if the word is not the last put a comma
         (actually we put a comma when there are more thand 3 item in words, but not in the last)
         */   
        }else if(i<words.length-1 ){ 
            sb.append(", ");  
        }

        /*if word[i] is the last of the array words we don't use nobody of the if!*/

        /*this code word on 0 1,2,3 ore more word in array words!*/
    }

    return sb.toString();
}

字符串数组到格式化的字符串

4 个答案: