Thread: linked list printing empty after removing duplicates

guys, I have a remove method that looks for duplicates and remove them; however, after I call that method my list appears to be empty, and that is b/c the "first" node is pointing to the last node in the list and of course there's nothing after that, and that is why is empty. How can I initialize it that it points back to the first node when calling the "display" method?

//remove duplicate records (return true if duplicate found)
    public boolean remove(String fn, String ln)
    {
        Node remove;
        boolean found = false;
        int duplicate = 0;
        while(first != null)
        {
            if(first.value.getFname().equals(fn) && first.value.getLname().equals(ln))
            {
                duplicate++;
                if(duplicate > 1)
                {
                    remove = first;
                    found = true;                      
                }                
            }
            first = first.next;
        }
        if(found)
            return found;
        else
            return found;
    }
 
    //display list of student
    public void display()
    {
        if(first == null)
            System.out.println("List is empty!");
        else
        {
            while(first != null)
            {
                System.out.println(first.value);
                first = first.next;
            }            
        }            
    }

main

public class Tester {
 
 
    public static void main(String[] args) {
 
        UnderGrad john = new UnderGrad("john", "doe", 2.7, "computer Science", "phisics");
        UnderGrad jorge = new UnderGrad("jorge", "vazquez", 3.8, "computer Science", "programming");
        UnderGrad john2 = new UnderGrad("john", "doe", 3.0, "Computer Engineering", "phisics");
 
        Advisor jim = new Advisor("jim", "smith");
 
        Grad jane = new Grad("jane", "doe", 3.0, "Electric Engineering", jim);       
 
 
        LinkedList students = new LinkedList();
 
        students.add(john);
        students.add(jorge);
        students.add(john2);
        students.add(jane);
 
//        students.display();
 
        System.out.println(students.remove("john", "doe"));
 
        students.display();
 
 }

output

run:
true
List is empty!
BUILD SUCCESSFUL (total time: 0 seconds)

yeah, I just write "return found"...

another solution is to use a local variable to iterate through the list; however, I'm still not removing anything... any help?

the program is pretty much the same code as shown above, but the remove method I changed.. now I'm removing the wrong "Student" instead of removing the duplicate node= "john doe"

public class LinkedList {
 
    private Node first;
 
    public LinkedList()
    {
        first = null;
    }
 
    //add students to the list
    public void add(Student s)
    {
        Node newNode = new Node(s);
        newNode.next = first;
        first = newNode;        
    }
 
    //remove duplicate records (return true if duplicate found)
    public boolean remove(String fn, String ln)
    {
        Student remove;
        boolean found = false;
        int duplicate = 0;
 
        for(Node iterator = first; iterator != null; iterator = iterator.next)
        {
            if(iterator.value.getFname().equals(fn) && iterator.value.getLname().equals(ln))
            {
                duplicate++;
                if(duplicate > 1)
                {
                    remove = first.value;
                    first = first.next;
                    return found = true;  
 
                }                
            }            
        }
        return found;
    }
 
    //display list of student
    public void display()
    {
        if(first == null)
            System.out.println("List is empty!");
        else
        {
            while(first != null)
            {
                System.out.println(first.value);
                first = first.next;
            }            
        }            
    }
 
}

main

public class Tester {
 
    public static void main(String[] args) {
 
        UnderGrad john = new UnderGrad("john", "doe", 2.7, "computer Science", "phisics");
        UnderGrad jorge = new UnderGrad("jorge", "vazquez", 3.8, "computer Science", "programming");
        UnderGrad john2 = new UnderGrad("john", "doe", 3.0, "Computer Engineering", "phisics");
 
        Advisor jim = new Advisor("jim", "smith");
 
        Grad jane = new Grad("jane", "mckee", 3.0, "Electric Engineering", jim);       
 
 
        LinkedList students = new LinkedList();
 
        students.add(john);
        students.add(jorge);
        students.add(john2);
        students.add(jane);
 
 
        System.out.println(students.remove("john", "doe"));
 
        students.display();  
 
    }
}

output

run:
true
john doe 3.0 Computer Engineering Good phisics
jorge vazquez 3.8 computer Science Good programming
john doe 2.7 computer Science Good phisics

yeah, I tried that... didn't help... thanks anyway. may be someone else would like to take a crack at this...