Question

我有一个方法应该计算句子中单词的出现并返回结果。由于某种原因，它不算数。代码始终返回0。

这是代码。

public static int countOccurance (String word, String sentence) {
int count = 0;
for (int i = 0; i != sentence.length()-word.length()-2; i++) {
    if (sentence.substring(i, i+word.length()-1).equalsIgnoreCase(word)) {
        count++;
    }
}
return count;
}

有谁能告诉我我的方法有什么问题？

Answer 1

您的子字符串已关闭，您的循环位置检查也不正确。当我将你的方法改为时，

public static int countOccurance(String word, String sentence) {
    int count = 0;
    for (int i = 0; i + word.length() < sentence.length(); i++) {
        if (sentence.substring(i, i + word.length()).equalsIgnoreCase(
                word)) {
            count++;
        }
    }
    return count;
}

public static void main(String[] args) {
    System.out.println(countOccurance("Hello", "hello hello world"));
    System.out.println(countOccurance("Fi", "Fee Fi Fum"));
}

它输出预期的

2
1

Answer 2

我刚拿走你的代码并删除你的-1和-2，因为我不明白为什么他们在那里。

public static int countOccurance (String word, String sentence) {
    int count = 0;
    for (int i = 0; i != sentence.length()-word.length(); i++) {
        if (sentence.substring(i, i+word.length()).equalsIgnoreCase(word)) {
            count++;
        }
    }
    return count;
}

试过这个。

String sentence = "yakkity yak yak yak attack";
String word = "yak";

int wc = countOccurance (word, sentence);

System.out.println("The string \""+sentence+"\" contains the word "+word+" "+wc+" times.");

结果：

The string "yakkity yak yak yak attack" contains the word yak 4 times.

Answer 3

最好是检查＆＃34; ＆＃34;空间,,,因为每个空间都要遇到...计数++ ..... 你也可以查看＆＃39; \ n＆＃39;在检查案件中并使循环结束于\ 0 string null character !!

Answer 4

我会使用正则表达式

    Matcher m= Pattern.compile("\\b" + word + "\\b").matcher(sentence);
    while(m.find()) {
        count++;
    }

Answer 5

在Collections.frequency()个单词上使用List方法，避免了自己跟踪计数器的全部需求：

 public static int countOccurance (String word, String sentence) {
     List<String> words = Arrays.asList(sentence.split(" "));
     return Collections.frequency(words,word);
 }

Answer 6

因为其他人已经说明了为什么您当前的代码不起作用，我想使用这个答案来提出建议。我个人建议使用Java的正则表达式API来解决这个问题。使用类似下面的内容;

public static int countOccurance (String regex, String sentence) {
    Pattern p = Pattern.compile(word);
    Matcher m = p.matcher(sentence);
    int count = 0;
    while(m.find()) count++;

    return count;
}

我希望这会有所帮助。

Official Java Regex Tutorials

Answer 7

您可以尝试以下代码：

public static void main(String[] args){
    String sentence = "Hello truc, Hello machi, and Hello all !";
    final String word = "hello";

    System.out.println(count(sentence.toLowerCase(), word.toLowerCase()));
}

public static int count(String sentence, String word){
    int cpt = 0;
    while(sentence.contains(word)){
        cpt++;
        sentence = sentence.substring(sentence.indexOf(word) + word.length());
    }
    return cpt;
}

单词出现方法不计

7 个答案: