how to create list of list in java code example

Example 1: how to create a list in java

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

class scratch{
    public static void main(String[] args) {
        List<Integer> aList = new ArrayList<>();
        List<Integer> lList = new LinkedList<>();
    }
}

Example 2: Lists inside lists in java

public class GuiTest {

	
	public static void main(String[] args) {
		List<List<Integer>> MainList = new ArrayList<List<Integer>>();
		Random NewRandomNumber = new Random();
		
		for (int i = 0; i < 10; i++) {
			List<Integer> SecondList = new ArrayList<Integer>();
			MainList.add(SecondList);
			for (int i2 = 0; i2 < 10; i2++) {
				SecondList.add(NewRandomNumber.nextInt(6));
			}
		}

Example 3: how to make java list

//Creating arraylist example 
ArrayList<String> list = new ArrayList<String>();  
 
//Adding objects in arraylist 
list.add("Mango");    
list.add("Banana");   

//Change the element (index,"new value")
list.set(1,"Dates"); 

//Return the 2nd element, because index starts from 0
System.out.println("Returning element: " + list.get(1));

Example 4: arraylist of arraylist

public static void main(String[] args) {
    ArrayList<ArrayList<Integer>> outer = new ArrayList<ArrayList<Integer>>();
    ArrayList<Integer> inner = new ArrayList<Integer>();        

    inner.add(100);     
    inner.add(200);
    outer.add(inner); // add first list
    inner = new ArrayList<Integer>(inner); // create a new inner list that has the same content as  
                                           // the original inner list
    outer.add(inner); // add second list

    outer.get(0).add(300); // changes only the first inner list

    System.out.println(outer);
}