Question

Suppose I insert 5 strings in an ArrayList. Will the order of insertion and retrieval from the ArrayList be the same?

Answer 1

Yes, ArrayList is an ordered collection and it maintains the insertion order.

Check the code below and run it:

public class ListExample {

    public static void main(String[] args) {
        List<String> myList = new ArrayList<String>();
        myList.add("one");
        myList.add("two");
        myList.add("three");
        myList.add("four");
        myList.add("five");
    
        System.out.println("Inserted in 'order': ");
        printList(myList);
        System.out.println("\n");
        System.out.println("Inserted out of 'order': ");

        // Clear the list
        myList.clear();
    
        myList.add("four");
        myList.add("five");
        myList.add("one");
        myList.add("two");
        myList.add("three");
    
        printList(myList);
    }

    private static void printList(List<String> myList) {
        for (String string : myList) {
            System.out.println(string);
        }
    }
}

Produces the following output:

Inserted in 'order': 
one
two
three
four
five


Inserted out of 'order': 
four
five
one
two
three

For detailed information, please refer to documentation: List (Java Platform SE7)