There are following way to add odd and even number into a single array in java 8.

• Here we add three list EvenNumbers, PrimeNumbers, OddNumbers into single list using List<List<Integer>> list.
• Now we Stream the data from List using arrayList.stream() method.
• Use flatMap() method to transforms each list of numbers into a stream of numbers.
• Now call the Collectors.toList() to store all number inside list.
• Finally, print the all 3 numbers into single array list on the console.

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

public class AddListData {
	public static void main(String[] args) {
		
		List<Integer> EvenNumbers = Arrays.asList(12, 14, 16, 18);
		List<Integer> PrimeNumbers = Arrays.asList(5, 7, 11, 13);
		List<Integer> OddNumbers = Arrays.asList(1, 3, 5);
		
		List<List<Integer>> list = Arrays.asList(EvenNumbers,PrimeNumbers, OddNumbers);
		List<Integer> listAdd = list.stream().flatMap(l -> l.stream()).collect(Collectors.toList());
		System.out.println("add prime,odd and even number into list :- " + listAdd);

	}
}

Output :-

add prime,odd and even number into list :- [12, 14, 16, 18, 5, 7, 11, 13, 1, 3, 5]