One-liner to count number of occurrences of String in a String[] in Java?

Question

I have an array of String:

String[] myArray = {\"A\", \"B\", \"B\", \"C\"};

Is there a quick way to count the number of occurrence

Answer 1

You can also try using Guava which is full of useful utilities. Using below code, you can count the frequency via Multiset:

public static void main(final String[] args) {
        String[] myArray = {"A", "B", "B", "C"};
        Multiset<String> wordsMultiset = HashMultiset.create();
        wordsMultiset.addAll(new ArrayList<String>(Arrays.asList(myArray)));
        int counts=wordsMultiset.count("B");
        System.out.println(counts);
    }

Although I know that you are looking for a single liner, but Guava is full of many more utils which are not possible with routine java utils.

Answer 2

You can use the frequency method:

List<String> list = Arrays.asList(myArray);
int count = Collections.frequency(list, "B");

or in one line:

int count = Collections.frequency(Arrays.asList(myArray), "B");

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With Java 8 you can also write:

long count = Arrays.stream(myArray).filter(s -> "B".equals(s)).count();

Or with a method reference:

long count = Arrays.stream(myArray).filter("B"::equals).count();