IntPredicateExample.java

package org.athenian._4_predicates;

import java.util.Arrays;
import java.util.function.Predicate;
import java.util.stream.Collectors;

public class IntPredicateExample {

    public static void main(String[] args) {
        // Verbose
        Predicate<Integer> isEvenVerbose =
                new Predicate<>() {
                    @Override
                    public boolean test(Integer val) {
                        return val % 2 == 0;
                    }
                };

        // Better
        Predicate<Integer> isEvenMedium = val -> {
            return val % 2 == 0;
        };

        // Terse
        Predicate<Integer> isEvenTerse = val -> val % 2 == 0;

        for (int i = 0; i < 10; i++)
            System.out.printf("%d %s%n", i, isEvenTerse.test(i));

        var vals = Arrays.asList(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10);

        var evens =
                vals.stream()
                    .filter(val -> val % 2 == 0)
                    .collect(Collectors.toList());

        var odds =
                vals.stream()
                    .filter(val -> !evens.contains(val))
                    .collect(Collectors.toList());

        System.out.println("Evens: " + evens);
        System.out.println("Odds: " + odds);
    }
}