Write the method

ArrayList<Integer> combine(ArrayList<Integer> list1, ArrayList<Integer> list2)

which takes as parameters two lists of integers. 
The lists are ordered in ascending order (i.e. the smallest number is first and the largest last).

The method returns a new list of integer type with all the elements of the parameter lists combined.
In the new list, the elements are also ordered in order of magnitude.



Example method call:
public static void main(String[] args){
    ArrayList<Integer> list1 = new ArrayList<>();
    list1.add(1);
    list1.add(3);
    list1.add(5);

    ArrayList<Integer> list2 = new ArrayList<>();
    list2.add(2);
    list2.add(4);
    list2.add(6);

    ArrayList<Integer> combined = combine(list1, list2);

    System.out.println(combined);
}
Program outputs:
[1, 2, 3, 4, 5, 6]



======================================



import java.util.Random;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;

public class Test{
    public static void main(String[] args){
        final Random r = new Random();
        
        testaa(new int[]{1,3,5,7,9}, new int[]{2,4,6,8,10});
        testaa(new int[]{10,20,30,40,50,60}, new int[]{70,80,90,100,110});
        testaa(new int[]{1,11,21,31,41}, new int[]{2,3,4,32,33,34,42});

        
        
    }
    
    public static void tulosta(ArrayList<String> lista) {
        System.out.print("[\"");
        System.out.print(String.join("\", \"", lista));
        System.out.println("\"]");
    }
    
    public static void testaa(int[] l1, int[] l2) {
        ArrayList<Integer> lista1 = new ArrayList<>();
        for (int a : l1) {
            lista1.add(a);
        }
        
        ArrayList<Integer> lista2 = new ArrayList<>();
        for (int a : l2) {
            lista2.add(a);
        }
        
        System.out.println("Testing with lists ");
        System.out.println("" + lista1);
        System.out.println("" + lista2);
        System.out.println("Combined: ");
        System.out.println(combine(lista1, lista2));
        System.out.println("");
    }
    
    
    


    // https://stackoverflow.com/a/189569/5324726
    // combine used by testaa
    public static ArrayList<Integer> combine(ArrayList<Integer> list1, ArrayList<Integer> list2){
        ArrayList<Integer> combined = new ArrayList<>();
        // for (int a : list1) {
        //     combined.add(a);
        // }
        // for (int a : list2) {
        //     combined.add(a);
        // }

        combined.addAll(list1);
        combined.addAll(list2);
        Collections.sort(combined);
        return combined;
    }




}





Testing with lists 
[1, 3, 5, 7, 9]
[2, 4, 6, 8, 10]
Combined: 
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

Testing with lists 
[10, 20, 30, 40, 50, 60]
[70, 80, 90, 100, 110]
Combined: 
[10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110]

Testing with lists 
[1, 11, 21, 31, 41]
[2, 3, 4, 32, 33, 34, 42]
Combined: 
[1, 2, 3, 4, 11, 21, 31, 32, 33, 34, 41, 42]