The interface or signatures of add() method is similar to the one discussed in case of an array. This method takes the object to be added as a parameter. The implementation of this add() method is a bit longer as the method is being implemented for linked list. In the first statement, a new Node object is created with its address stored in the newNode pointer variable. The second statement is to call set() method of the Node object pointed to by the newNode pointer. You can note the way the method is called. A pointer variable is at the left most side then an arrow sign (->), then the name of the method with appropriate arguments within parenthesis. It is followed by the if-statement that checks the currentNode is not NULL to perform certain operations inside the if-code block. Inside the if-statement, at line 5, the nextNode pointer of the new node is being set to the nextNode of the object pointed to by the currentNode pointer. In order to understand the statements given in this code properly, consider the previous figure, where we added a node in the linked list in steps. We have done step 1 at line5. At line 6, we are performing the second step by setting the newNode in the nextNode pointer of the object pointed to by the currentNode. At line 7, we are saving the current position (address) of the currentNode pointer in the pointer variable lastCurrentNode, which might be useful for backward traversing. Although, the diagrams indicate movement in one direction from left to right but the lastCurrentNode pointer node can be used by the back() member function to traverse one position back from right to left. At line 8, the currentNode pointer is assigned the address of the object pointed to by newNode. This way, a new node is added in already existent linked list. Line 10 is start of the else part of if-statement. This is executed if the currentNode is NULL. It means that there is no node present in the list previously and first node is going to be added. At line 12, we are setting the nextNode pointer of the object pointed to by newNode pointer. The nextNode is being set to NULL by calling the setNext() method. Then at line 13, we point the head pointer (headNode) to this new node pointed to by newNode pointer. Note that headNode is pointing to a node that is there despite the fact that the size of the linked list is 0. Actually, we have allocated a Node object for headNode pointer. Although, we don’t need a Node object here, yet it will be helpful when we perform other operations like remove() and find(). At line 14, the headNode address is being assigned to lastCurrentNode. At line 15, currentNode pointer is assigned the address of newNode. At the end i.e. at line 17, the size of the list is incremented by 1.
	BACK	HOME	NEXT