Hi! I have a method that inserts a node but does not check whether the item to b

Question

Hi! I have a method that inserts a node but does not check whether the item to be inserted is already in the list. I need it modified to check for duplicates. Thanks!


public void insertNode(DataElement insertItem)
{
LinkedListNode current; //variable to traverse the list
LinkedListNode trailCurrent; //variable just before current
LinkedListNode newNode; //variable to create a node

boolean found;

newNode = new LinkedListNode(); //create the node
newNode.info = insertItem.getCopy(); //store newItem in the node
newNode.link = null; //set the link field of the node to null

if(first == null) //Case 1
{
first = newNode;
count++;
}
else
{
trailCurrent = first;
current = first;
found = false;

while(current != null && !found) //search the list
if(current.info.compareTo(insertItem) >= 0)
found = true;
else
{
trailCurrent = current;
}

if(current == first) //Case 2
{
newNode.link = first;
first = newNode;
count++;
}
else //Case 3
{
trailCurrent.link = newNode;
newNode.link = current;
count++;
}
}
}

Explanation / Answer

public void insertNode(DataElement insertItem)
{
LinkedListNode current; //variable to traverse the list
LinkedListNode trailCurrent; //variable just before current
LinkedListNode newNode; //variable to create a node

boolean found;

newNode = new LinkedListNode(); //create the node
newNode.info = insertItem.getCopy(); //store newItem in the node
newNode.link = null; //set the link field of the node to null

if(first == null) //Case 1
{
first = newNode;
count++;
}
else
{
trailCurrent = first;
current = first;
found = false;

while(current != null && !found) //search the list
if(current.info.compareTo(insertItem) >= 0)
found = true;
else
{
trailCurrent = current;
}

if(found)
{
system.out.println("Item already exist, do u want to insert anyway..(Y/N)");
char myChar = (char) System.Console.Read();
if (mychar=='n' ||mychar=='N')
exit(0);
}


if(current == first) //Case 2
{
newNode.link = first;
first = newNode;
count++;
}
else //Case 3
{
trailCurrent.link = newNode;
newNode.link = current;
count++;
}
}
}

Note:

In the lines written in RED, i have checked whether the item is found or not.

If found i will aks the user that it already exist ,do u want to add anyway.

If he will enter yes then i will continue

if he will enter NO i will exit from the function.

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