LinkedList in java

Let’s learn LinkedList in java.

LinkedList in java

Properties of LinkedList:

• The underlying data structure of LinkedList is Double LinkedList.
• Insertion order is preserved. That is order in which the elements is inserted is retrieved back in the same order.
• Heterogeneous objects are allowed.
• Null insertion is allowed.
• LinkedList implements Serializable and Cloneable interfaces. Not RandomAccess Interface.
• LinkedList is best if our frequent operation is insertion or deletion in the middle.
• Do not use LinkedList if our frequent operation is retrieval from LinkedList.

Methods in LinkedList

Here’s the list of LinkedList specific methods.

void addFirst(); Inserts the specified element at the beginning of this list.

void addLast(); Appends the specified element to the end of this list.

Object getFirst(); Returns the first element in this list.

Object getLast(); Returns the last element in this list.

Object removeFirst(); Removes and returns the first element from this list.

Object removeLast(); Removes and returns the last element from this list.

Constructors in LinkedList

LinkedList ll = new LinkedList(); creates an empty LinkedList object.

LinkedList ll = new LinkedList(Collection c); creates an equivalent LinkedList object for the given Collection.

Now let us execute a java program on LinkedList.

import java.util.LinkedList;
class LinkedListDemo
{
    public static void main(String[] args)
    {
        LinkedList ll = new LinkedList();
        ll.add("deepa");
        ll.add(60);
        ll.add(null);
        ll.add("deepa");
        ll.set(0, "sangeetha");
        ll.add(0, "virat");
        ll.removeLast();
        ll.addFirst("chethan");
        System.out.println(ll);
        ll.removeLast();
    }
}

Output:

[chethan, virat, sangeetha, 60, null]

Difference between ArrayList and LinkedList