java add a list to a list

List mylist.addAll(secondList);

List<SomePojo> list = new ArrayList<SomePojo>();

List<SomePojo> anotherList = new ArrayList<SomePojo>();
anotherList.add(list);

package com.journaldev.examples;

import java.util.ArrayList;
import java.util.List;

public class ListAddExamples {

	public static void main(String[] args) {

		List<String> vowels = new ArrayList<>();

		vowels.add("A"); // [A]
		vowels.add("E"); // [A, E]
		vowels.add("U"); // [A, E, U]

		System.out.println(vowels); // [A, E, U]

		vowels.add(2, "I"); // [A, E, I, U]
		vowels.add(3, "O"); // [A, E, I, O, U]

		System.out.println(vowels); // [A, E, I, O, U]
	}
}

List<String> newList = Stream.concat(listOne.stream(), listTwo.stream())
                             .collect(Collectors.toList());