Doubly-linked list insert method

boolean insert(T newObject){
        //Create new node
        Node newNode = new Node(newObject);

        //If list is empty
        if (numberOfEntries == 0) {
            firstNode = newNode;
            lastNode = newNode;
            currentNode = newNode;
        }

        //Reassign previous and next of current node to new node
        newNode.previous = currentNode.previous;
        currentNode.previous = newNode;
        newNode.next = currentNode;

        //Change next of new node's previous node
        if (newNode.previous != null){
            newNode.previous.next = newNode;
        }
        //If the previous of new node is null, it will become the new first node
        else {
            firstNode = newNode;
        }

        numberOfEntries++;

        return true;
    }