Practice›Java Fundamentals›Module 10. Collections›10.4 Patterns

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10.4 Patterns — count items not in a set

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Task

Fill in countMissing so that it returns how many elements of have are not present in known, counting every occurrence.

Put known into a set first, then test each element of have. The program prints 2 — both copies of x.

Your solution

import java.util.HashSet;
import java.util.Set;

public class Main {

    public static int countMissing(String[] have, String[] known) {
        // count elements of have that are NOT in known

    }

    public static void main(String[] args) {
        System.out.println(countMissing(new String[]{"x", "y", "z", "x"}, new String[]{"y", "z"}));
    }
}

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