java Linked list problem

I am now struggling my assignment, the assignment require me to re-
implement the previous lab using a linked list;
I read the instruction, it seems to let me implement something like
the following diagram:
RecordList------>RecordNode------->RecordNode-------->RecordNode---
and each RecordNode includes a Customer information; in Customer
class:
I have the following methods and functions:

class Customer implements Comparable{ //
implements Comparator{
    private int accountid;
    private String name, address, dateofbirth, phoneNo, accType;
    protected double balance;
    protected double interestRate;

    //protected double updatebal;
    public Customer(){
        accountid = 0;
        name = address = dateofbirth = phoneNo = accType = null;
        balance = interestRate = 0.0;

    }
    public Customer(int id, String n, String a, String d, String p,
            String t, double b, double i){
        accountid = id;
        name = n;
        address = a;
        dateofbirth = d;
        phoneNo = p;
        accType = t;
        balance = b;
        interestRate = i;

    }

    public void setAccId(int accid){
        accountid = accid;
    }

    public void setName(String n){
        name = n;
    }

    public void setAddress(String add){
        address = add;
    }

    public void setDOB(String dOfbirth){
        dateofbirth = dOfbirth;
    }

    public void setPhone(String p){
        phoneNo = p;
    }

    public void setBal(double bal){
        balance = bal;
    }

    public void setAccType(String accType){
        this.accType = accType;
    }

    public int getAccId(){
        return accountid;
    }

    public String getName(){
        return name;
    }

    public String getAddress(){
        return address;
    }

    public String getDOB(){
        return dateofbirth;
    }

    public String getPhone(){
        return phoneNo;

    }

    public double getBal(){
        return balance;
    }

    public String getAccType(){
        return accType;
    }

    // Interest Rate for fixed Account
    public void setInterestRate(double iRate){
        interestRate = iRate;
    }

    // Get method for interest rate
    public double getInterestRate(){
        return interestRate;

    }

    public void update(){
        ///return 0;
    }

    public int compareTo(Object o){
        if(!(o instanceof Customer)){
            throw new IllegalArgumentException("Err: non-Record type
object");
        }
        Customer c = (Customer)o;
        if(accountid>c.accountid) return 1;
        if(accountid<c.accountid) return -1;
        return 0;
    }

    @Override
    public String toString(){
        return "Customer(" + getAccId() + "): " + getName();
    }

    @Override
    public Customer clone(){
        Customer r = new Customer(accountid,name,address,dateofbirth,
                phoneNo,accType,balance,interestRate);
        return r;
    }
}

That means, by far, I have RecordList.java, RecordNode.java,
Customer.java, Main.java
In Main, I try to read data from file containg the customers
information(i.e. id,name,account balance,etc.)
One of my function is to check whether 2 account id is duplicated.
<---- I am stranding in this part, how can
I check the 2 record nodes containing the same id and remove it?.

the following code is the Readfile function in Main:
// I don't know how to use RecordList rList here?
    static int readFile(File inputfile,RecordList rList){
        try{

            FileInputStream fis = new FileInputStream(inputfile);
            BufferedInputStream bis = new BufferedInputStream(fis);
            DataInputStream fileinput = new DataInputStream(bis);
            BufferedReader br = new BufferedReader(new
InputStreamReader(fileinput));
            String read;
            int i = 1;
            Customer temp = new Customer();
                while((read=br.readLine())!=null){

                    if(read.contains("Account Id = ")){
                         String caid =
read.substring(read.lastIndexOf("=") + 2);
                         temp.setAccId(Integer.parseInt(caid));

                    }
                    else if(read.contains("Name = ")){
                        String cname =
read.substring(read.lastIndexOf("=") + 2);
                        if(cname.length()< )
temp.setName(cname.toUpperCase());
                    }
                    else if(read.contains("Address = ")){
                        String caddress =
read.substring(read.lastIndexOf("=") + 2);
                        if(caddress.length()<=80)
temp.setAddress(caddress);
                    }
                    else if(read.contains("DOB = ")){
                        String cdob =
read.substring(read.lastIndexOf("=") + 2);
                        if(cdob.length()<=10)
temp.setDOB(cdob);
                    }
                    else if(read.contains("Phone Number = ")){
                        String cphoneno =
read.substring(read.lastIndexOf("=") +2);
                        if(cphoneno.length()<=8)
temp.setPhone(cphoneno);
                    }
                    else if(read.contains("Account Balance = ")){
                        String caccbal =
read.substring(read.lastIndexOf("=")+2);
                        double accbal = Double.parseDouble(caccbal);
                        temp.setBal(accbal);

                    }
                    else if(read.contains("Account Type = ")){
                        String caactype =
read.substring(read.lastIndexOf("=") + 2);
                        if(caactype.length()<=8)
temp.setAccType(caactype);

                        if(temp.getAccType().equals("Saving")){
                            rList.insert(i,temp);
                        }
                        else if(temp.getAccType().equals("Checking")){
                            rList.insert(i,temp);
                        }
                        else if(temp.getAccType().equals("Fixed")){
                            read=br.readLine();
                            if(read.contains("Fixed Daily Interest =
")){
                                String cintrate =
read.substring(read.lastIndexOf("=")+2);
                                double intrate =
Double.parseDouble(cintrate);
                                temp.setInterestRate(intrate);
                                rList.insert(i,temp);

                            }
                            else System.out.println("Sorry, no daily
interest found!");

                        }

                        i++;
                    }
                }

            fileinput.close();
            return i-1;
            // i-1 returns the record successfully read;
        }
        catch (IOException ex){
            System.err.println(ex);
        }

        return 0;
    }

How can I implement a function checking 2 recordnodes is duplicated
here?

The following is RecordNode and RecordList code:

// RecordNode

public class RecordNode{
   private Object item;
   private RecordNode next;

   public RecordNode(Object o){
       o = item;
       next = null;
   }

   public RecordNode(Object o, RecordNode newNext){
       o = item;
       next = newNext;
   }

   public void setItem(Object o){
       item = o;
   }

   public Object getItem(){
       return item;
   }

   public void setNext(RecordNode newNext){
       next = newNext;
   }

   public RecordNode getNext(){
       return next;
   }
}

// RecordList
public class RecordList {
    protected int numItem;
    protected RecordNode head;

    public RecordList(){
        head = null;
        numItem = 0;

    }

    public RecordList(RecordNode newNode){
        head = newNode;
        numItem ++;
    }

    public boolean isEmpty(){

        return (numItem==0)? true:false;
    }

    public int getSize(){
        return numItem;
    }

    public Object getItem(int index){
        if(index>numItem) return null;
        return find(index).getItem();
    }

    // find current node;
    public RecordNode find(int index){
        RecordNode cur = head;
        if(index>numItem) return null;
        for(int i = 1;i<index;i++)
            cur = cur.getNext();
        return cur;
    }

    public boolean insert(int at, Object newItem){
        RecordNode pre,cur;
        if(at < 1 || at > numItem+1) return false;
        numItem++;

        if(at == 1){
            if(isEmpty()) head = new RecordNode(newItem);
            else head = new RecordNode(newItem,head);
            return true;
        }

        pre = find(at-1);
        cur =pre.getNext();
        pre.setNext(new RecordNode(newItem, cur));
        return true;
    }

}

// This following part is not yet done.
and inside the Customer class, there should be a transaction linked
list for recording the transaction of
each customer, something like:
Inside the Customer:
TransactionList--->TransactionNode------->TransactionNode--------
// This part I've not done yet.

I am sorry the question is too long.