How to properly make a concat List?

Question

Java

Hello everyone, can you tell me how correct this approach is for concatenating lists using the Stream API concat?

import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;

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

        List<Integer> list1 = new ArrayList<>();
        List<Integer> list2 = new ArrayList<>();
        List<Integer> list3;

        list1.add(1);
        list1.add(2);
        list1.add(3);
        list1.add(4);
        list1.add(5);
        list2.add(6);
        list2.add(7);
        list2.add(8);
        list2.add(9);
        list2.add(10);

        System.out.println(list1);
        System.out.println(list2);

        Stream<Integer> stream1 = Stream.concat(list1.stream(), list2.stream());
        System.out.println(stream1);

        list3 = (List<Integer>) stream1.collect(Collectors.toList());

        System.out.println(list3);

    }
}

Answer 1

Just uselist.addAll