arraylist of arraylist

1public class GuiTest {
2
3	
4	public static void main(String[] args) {
5		List<List<Integer>> MainList = new ArrayList<List<Integer>>();
6		Random NewRandomNumber = new Random();
7		
8		for (int i = 0; i < 10; i++) {
9			List<Integer> SecondList = new ArrayList<Integer>();
10			MainList.add(SecondList);
11			for (int i2 = 0; i2 < 10; i2++) {
12				SecondList.add(NewRandomNumber.nextInt(6));
13			}
14		}

1import java.util.ArrayList;
2ArrayList<Integer> myList = new ArrayList<Integer>();
3myList.add(0);
4myList.remove(0);//Remove at index 0
5myList.size();
6myList.get(0);//Return element at index 0

1// THIS IS OKAY:
2ArrayList arrayList = new ArrayList();

1ArrayList<String>arrayList=new ArrayList<>();

1public static void main(String[] args) {
2    ArrayList<ArrayList<Integer>> outer = new ArrayList<ArrayList<Integer>>();
3    ArrayList<Integer> inner = new ArrayList<Integer>();        
4
5    inner.add(100);     
6    inner.add(200);
7    outer.add(inner); // add first list
8    inner = new ArrayList<Integer>(inner); // create a new inner list that has the same content as  
9                                           // the original inner list
10    outer.add(inner); // add second list
11
12    outer.get(0).add(300); // changes only the first inner list
13
14    System.out.println(outer);
15}