java Pair.java

Posted 2021-05-08

import java.util.stream.Stream;

public class Test {
    public static void main(String args[]) {

        Stream.of(1, 2, 3, 4, 5).map(i -> new Pair(i, i)).reduce(
                new Pair(0, 0),
                (acc, pair) -> new Pair(acc.fst + pair.fst, acc.snd + pair.snd)
        );

        System.out.println(Stream.of(1, 2, 3, 4, 5).reduce(
                new Pair(0, 0),
                Pair::add,
                Pair::combine
        ));
    }
}

public class Pair {
    public final int fst;
    public final int snd;

    public Pair(int fsn, int snd) {
        this.fst = fsn;
        this.snd = snd;
    }

    public Pair add(int i) {
        return new Pair(fst + i, snd + i);
    }

    public Pair combine(Pair target) {
        return new Pair(fst + target.fst, target.snd);
    }

    @Override
    public String toString() {
        return "(" + fst + ", " + snd + ')';
    }
}