CODE EXAMPLE FOR JAVA

list of list in java

// Java code to demonstrate the concept of
// list of lists using iterator
  
import java.util.*;
  
class List_of_list {
  
    // Iterate the 2D list using Iterator
    // and print each element
    public static <K> void
    iterateUsingIterator(List<List<K> > listOfLists)
    {
        // Iterator for the 2D list
        Iterator listOfListsIterator
            = listOfLists.iterator();
  
        System.out.println("[");
        while (listOfListsIterator.hasNext()) {
  
            // Type cast next() method
            // to convert from Object to List<K>
            List<K> list = new ArrayList<K>();
  
            list = (List<K>)listOfListsIterator.next();
  
            // Iterator for list
            Iterator eachListIterator
                = list.iterator();
  
            System.out.print("  [");
            while (eachListIterator.hasNext()) {
  
                System.out.print(
                    "  "
                    + eachListIterator.next()
                    + ", ");
            }
            System.out.println("], ");
        }
        System.out.println("]");
    }
  
    // Driver code
    public static void main(String[] args)
    {
  
        // List of Lists
        ArrayList<List<Integer> > listOfLists
            = new ArrayList<List<Integer> >();
  
        // Create N lists one by one
        // and append to the list of lists
        List<Integer> list1
            = new ArrayList<Integer>();
        list1.add(5);
        list1.add(10);
        listOfLists.add(list1);
  
        List<Integer> list2
            = new ArrayList<Integer>();
        list2.add(1);
        listOfLists.add(list2);
  
        List<Integer> list3
            = new ArrayList<Integer>();
        list3.add(20);
        list3.add(30);
        list3.add(40);
        listOfLists.add(list3);
  
        // Iterate the 2D list
        iterateUsingIterator(listOfLists);
    }
}