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javadata-structureslinked-list

Linked List addLast() method is not working as expected

As per the definition addLast(), the addLast() method is used to add element to the last of the list. But here in the following code that's not happening.

LinkedList<Integer> demo = new LinkedList<>();
demo.addLast(15);
demo.addFirst(1);
demo.add(10);
System.out.println(demo);

The output is

[1, 15, 10]

But as per the definition the output should have been

[1, 10, 15]

Because the addLast() method should be adding 15 to the last of the list. I'm not sure what exactly is the issue here.

Code snippet : Code snippet

Solution

  • addLast adds an item at the end of the list - it doesn't mean it will remain at the end of list when additional items are added.

    Let's track the code:

    • you start with an empty list.
    • addLast(15) will add 15 at the end of this list, so it's now [15]
    • addFirst(1) will add 1 at the beginning of the list, so it's now [1, 15]
    • add(10) will add 10 at the end of the list, so it's now [1, 15, 10]