Count the number of Occurrences of a Word in a String

Question

I am new to Java Strings the problem is that I want to count the Occurrences of a specific word in a String. Suppose that my String is:

i have a male cat. the color of male cat is Black

Now I dont want to split it as well so I want to search for a word that is "male cat". it occurs two times in my string!

What I am trying is:

int c = 0;
for (int j = 0; j < text.length(); j++) {
    if (text.contains("male cat")) {
        c += 1;
    }
}

System.out.println("counter=" + c);

it gives me 46 counter value! So whats the solution?

Answer 1

You can use the following code:

String in = "i have a male cat. the color of male cat is Black";
int i = 0;
Pattern p = Pattern.compile("male cat");
Matcher m = p.matcher( in );
while (m.find()) {
    i++;
}
System.out.println(i); // Prints 2

Demo

What it does?

It matches "male cat".

while(m.find())

indicates, do whatever is given inside the loop while m finds a match. And I'm incrementing the value of i by i++, so obviously, this gives number of male cat a string has got.

Answer 2

If you just want the count of "male cat" then I would just do it like this:

String str = "i have a male cat. the color of male cat is Black";
int c = str.split("male cat").length - 1;
System.out.println(c);

and if you want to make sure that "female cat" is not matched then use \\b word boundaries in the split regex:

int c = str.split("\\bmale cat\\b").length - 1;

Answer 3

StringUtils in apache commons-lang have CountMatches method to counts the number of occurrences of one String in another.

   String input = "i have a male cat. the color of male cat is Black";
   int occurance = StringUtils.countMatches(input, "male cat");
   System.out.println(occurance);

Answer 4

Java 8 version:

    public static long countNumberOfOccurrencesOfWordInString(String msg, String target) {
    return Arrays.stream(msg.split("[ ,\\.]")).filter(s -> s.equals(target)).count();
}

Answer 5

This static method does returns the number of occurrences of a string on another string.

/**
 * Returns the number of appearances that a string have on another string.
 * 
 * @param source    a string to use as source of the match
 * @param sentence  a string that is a substring of source
 * @return the number of occurrences of sentence on source 
 */
public static int numberOfOccurrences(String source, String sentence) {
    int occurrences = 0;

    if (source.contains(sentence)) {
        int withSentenceLength    = source.length();
        int withoutSentenceLength = source.replace(sentence, "").length();
        occurrences = (withSentenceLength - withoutSentenceLength) / sentence.length();
    }

    return occurrences;
}

Tests:

String source = "Hello World!";
numberOfOccurrences(source, "Hello World!");   // 1
numberOfOccurrences(source, "ello W");         // 1
numberOfOccurrences(source, "l");              // 3
numberOfOccurrences(source, "fun");            // 0
numberOfOccurrences(source, "Hello");          // 1

---

BTW, the method could be written in one line, awful, but it also works :)

public static int numberOfOccurrences(String source, String sentence) {
    return (source.contains(sentence)) ? (source.length() - source.replace(sentence, "").length()) / sentence.length() : 0;
}