Saturday, July 25, 2026
HomeLanguagesJavaArrayList of ArrayList in Java

ArrayList of ArrayList in Java

We have discussed that an array of ArrayList is not possible without warning. A better idea is to use ArrayList of ArrayList.




// Java code to demonstrate the concept of
// array of ArrayList
  
import java.util.*;
public class Arraylist {
    public static void main(String[] args)
    {
        int n = 3;
  
        // Here aList is an ArrayList of ArrayLists
        ArrayList<ArrayList<Integer> > aList = 
                  new ArrayList<ArrayList<Integer> >(n);
  
        // Create n lists one by one and append to the 
        // master list (ArrayList of ArrayList)
        ArrayList<Integer> a1 = new ArrayList<Integer>();
        a1.add(1);
        a1.add(2);
        aList.add(a1);
  
        ArrayList<Integer> a2 = new ArrayList<Integer>();
        a2.add(5);
        aList.add(a2);
  
        ArrayList<Integer> a3 = new ArrayList<Integer>();
        a3.add(10);
        a3.add(20);
        a3.add(30);
        aList.add(a3);
  
        for (int i = 0; i < aList.size(); i++) {
            for (int j = 0; j < aList.get(i).size(); j++) {
                System.out.print(aList.get(i).get(j) + " ");
            }
            System.out.println();
        }
    }
}


Output:

1 2 
5 
10 20 30
RELATED ARTICLES

2 COMMENTS

Most Popular

Dominic
32520 POSTS0 COMMENTS
Milvus
131 POSTS0 COMMENTS
Nango Kala
6903 POSTS0 COMMENTS
Nicole Veronica
12017 POSTS0 COMMENTS
Nokonwaba Nkukhwana
12115 POSTS0 COMMENTS
Shaida Kate Naidoo
7023 POSTS0 COMMENTS
Ted Musemwa
7265 POSTS0 COMMENTS
Thapelo Manthata
6980 POSTS0 COMMENTS
Umr Jansen
6972 POSTS0 COMMENTS