Javaで2つのリストの差をとる

diff.java

import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;

public class Main {
    public static void main(String[] args) throws Exception {
        List<Integer> before = Arrays.asList(1,2,3,4,5);
        List<Integer> after = Arrays.asList(1,4,5,6);

        System.out.print("removed:");
        System.out.println(before.stream().filter(e -> !after.contains(e)).map(Object::toString).collect(Collectors.joining(",")));

        System.out.print("added:");
        System.out.println(after.stream().filter(e -> !before.contains(e)).map(Object::toString).collect(Collectors.joining(",")));
    }
}