why am I getting an endless loop in this implementation of addlast to linkedlist

guys, I'm trying to implement an "addLast" method of a LinkedList; however, I'm getting an endless loop.... could anyone help

Code :

---

public void addLast(int n)
    {
        Node p = new Node(n);
 
        if(first == null)
        {
            p.next = first;
            first = p;
        }
        else
        {
            Node current = first;
            while(current != null)
            {
                System.out.println("here!");
                if(current.next == null)
                {
                    current.next = p;
                }
                current = current.next;
            }
        }
    }

---

Think about how you are looping...write the process out on paper if you have to....when the current node's next element is null, you set it the the 'p' node. You loop once more, seeing that the current (which is now p) next node is null, so you set it's next element to p (or itself) - hence there will not be a non-null next element again (circular reference)

while(current != null)
{
System.out.println("here!");
if(current.next == null)
{
current.next = p;
}
current = current.next;

Ok, so if the next Node is null, then current.next, a.k.a. the next node, is made p. Then after adding p, which it does right away, current.next won't be null, hence an infinite loop.

else
{
Node current = first;
while(current.next != null)
{
System.out.println("here!");

current = current.next;
}

current.next = p;
p.next = null;

}

Thank you guys, it was so simple as to adding a "break" line

to: javapenguin

oh this one is very simple too... I just added a "break" line to mine

Quote:

---

Originally Posted by javapenguin

else
{
Node current = first;
while(current.next != null)
{
System.out.println("here!");

current = current.next;
}

current.next = p;
p.next = null;

}

---

is it necessary to assign "p.next = null"?.... it is already null right?

Quote:

---

it is already null right?

---

Add a println to the code to print out its value before you set it to null to see what its value is.