Question

我试图找出句子中单词出现的总数。我尝试了以下代码：

String str = "This is stackoverflow and you will find great solutions  here.stackoverflowstackoverflow is a large community of talented coders.It hepls you to find solutions for every complex problems.";

    String findStr = "hello World";     
    String[] split=findStr.split(" ");

    for(int i=0;i<split.length;i++){
        System.out.println(split[i]);
        String indexWord=split[i];
        int lastIndex = 0;
        int count = 0;      
        while(lastIndex != -1){

            lastIndex = str.indexOf(indexWord,lastIndex);
            System.out.println(lastIndex);

            if(lastIndex != -1){
                count ++;
                lastIndex += findStr.length();
            }

        }
        System.out.println("Count for word "+indexWord+" is : "+count);
    }

如果我传递的字符串就像“堆栈解决方案”一样，字符串应该分成两个（空格分割），并且需要找到句子中每个字符串出现的次数。如果我只传递一个字，则计数是完美的。代码必须匹配包含搜索字符串的子字符串。例如： - 在句子“堆叠”中出现三次，但计数只有2次。

感谢。

Answer 1

在匹配后递增lastIndex时，您的意思是将其增加匹配的长度（indexWord），而不是输入字符串的长度（findStr）。只需替换

行

lastIndex += findStr.length();

与

lastIndex += indexWord.length();

Answer 2

试试这段代码

String str = "helloslkhellodjladfjhello";
String findStr = "hello";
int lastIndex = 0;
int count = 0;

while(lastIndex != -1){

lastIndex = str.indexOf(findStr,lastIndex);

 if(lastIndex != -1){
    count ++;
    lastIndex += findStr.length();
 }
}
System.out.println(count);

Answer 3

您也可以使用地图。

public static void main(String[] args) {

        String value = "This is simple sting with simple have two occurence";

        Map<String, Integer> map = new HashMap<>();
        for (String w : value.split(" ")) {
            if (!w.equals("")) {

                Integer n = map.get(w);
                n = (n == null) ? 1 : ++n;
                map.put(w, n);
            }
        }
        System.out.println("map" + map);
    }

Answer 4

是否有任何理由不使用现成的API解决方案。这可以通过在apache commons-lang中使用StringUtils来实现，它具有CountMatches方法来计算一个String在另一个String中出现的次数。

E.g。

String input = "This is stackoverflow and you will find great solutions  here.stackoverflowstackoverflow is a large community of talented coders.It hepls you to find solutions for every complex problems.";
String findStr = "stackoverflow is";
for (String s : Arrays.asList(findStr.split(" "))) {
         int occurance = StringUtils.countMatches(input, s);
         System.out.println(occurance);
}

如何获得句子中单词出现的总数

4 个答案: