Practice›Java Fundamentals›Module 11. Modern Java›11.4 Lambdas and streams

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11.4 Lambdas and streams — count with a predicate

Total: 0 / 3 pts

Practice mode — check each part and get hints as you go.

Task

Fill in countMatching so that it returns how many elements satisfy the predicate p.

The caller supplies a lambda: x -> x > 0 counts positives, x -> x % 2 == 0 counts evens — the same method, different behaviour passed in. The program prints 3 and then 2.

Your solution

interface IntPredicate2 {
    boolean test(int x);
}

public class Main {

    public static int countMatching(int[] arr, IntPredicate2 p) {
        // call p.test on each element and count the matches

    }

    public static void main(String[] args) {
        int[] nums = {3, -1, 4, -2, 5};
        System.out.println(countMatching(nums, x -> x > 0));
        System.out.println(countMatching(nums, x -> x % 2 == 0));
    }
}

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