How to implement inputing data from a get method?

My program is to insert a Transaction data type into each Customer's
Transaction list by using linked list, by far, when I debug to here:
--------------------------------------------------------------------------------------------------------------
                    ((Customer)rList.getItem(j)).getTransList().
 
transinsertAcd((Trans)transList.getItem(i));
 
System.out.println(((Customer)rList.getItem(j)).getTransList().getSize());
-----------------------------------------------------------------------------------------------------------------
it seems the transinserAcd( ) cannot work and the size is always
zero. I think it is the problem with using getItem(j). so i want to
ask is it when using get method , it can only get sth but cannot write
sth into after get().xxx()(e.g), right? if it is, how can i do that?
or my concept is wrong?

my problem has following classes:

Customer.class---------store the data of a customer and every customer
has a transactionsortedList
CustomerNode.class------node to store customer type
CustomerList.class-------list to store customer node
CustomerSortedList.class---------extends to customerList and it sorts
the cusotmer type in acd order.
Main.class
Transaction.class-------store the data of a transaction (each customer
may has several transaction or no transactions)
TransactionNode.class----node to store transaction type
TransactionList.class------list to link the transaction node together
TransactionSortedList.class------extends to transactionList and it
sorts the transaction type in acd order.

---------------------Following is part of my main.class
code-------------------------------------------
  static int insert_trans(File inputfile,TransSortedList transList){
        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;
            //int lastid;
            //Customer temp = new Customer();
            Trans temp = new Trans();
            String[] tempread = null;

            //Customer cust;\
            br.readLine();
            br.readLine();
            while((read=br.readLine())!=null){
                tempread = read.split("\\s+");

                // set transaction id
                int caid = Integer.parseInt(tempread[0]);
                temp.setAccid(caid);

                // set transaction date
                String cdate = tempread[1];
                temp.setDate(cdate);

                // set transaction time
                String ctime = tempread[2];
                temp.setTime(ctime);

                // set transaction time
                String ctype = tempread[3];
                temp.setType(ctype);

                // set transaction amount
                double camount = Double.parseDouble(tempread[4]);
                temp.setAmount(camount);

                // set transaction location
                int cloc = Integer.parseInt(tempread[5]);
                temp.setLocation(cloc);
                transList.transinsertAcd(temp);
                i++;
            }

            lettrans(transList);
            fileinput.close();
            return i-1;
        }
        catch (IOException ex){
            System.err.println(ex);
        }

        return 0;
    }

    // let every customer has a transaction list
    // insert transactions which belong to each customer
    public static void lettrans(TransSortedList transList){
        boolean match;
        int matchid=0;
        Customer temp;
        Trans tTemp ;
//use this: tTemp.getAccid();
        for(int i = 1;i<=transList.getSize();i++){
            match = false;
            matchid = i;
            for(int j = 1;j<=rList.getSize();j++){
                if(((Customer)rList.getItem(j)).getAccId()==
                        ((Trans)transList.getItem(i)).getAccid())
{
                    ((Customer)rList.getItem(j)).getTransList().
 
transinsertAcd((Trans)transList.getItem(i));
 
System.out.println(((Customer)rList.getItem(j)).getTransList().getSize());
                    match = true;
                }
            }

            if(!match){
                System.out.print("Error: cannot find account" +
                        " number for transaction \"");
 
System.out.print(((Trans)transList.getItem(matchid)).getAccid() + "
");
 
System.out.print(((Trans)transList.getItem(matchid)).getDate() + " ");
 
System.out.print(((Trans)transList.getItem(matchid)).getTime() + " ");
 
System.out.print(((Trans)transList.getItem(matchid)).getType() + " ");
 
System.out.print(((Trans)transList.getItem(matchid)).getAmount() + "
");
 
System.out.print(((Trans)transList.getItem(matchid)).getLocation());
                System.out.print("\"");
                System.out.println();
            }
        }
    }
-------------------------------The transactions.txt is like
this---------------------------------------
accountNumber date time type amount place

65 12-09-2008 1200 debit 500.00 1
123 12-09-2008 1200 debit 100.00 1
17 14-09-2008 1300 credit 100.00 2
67 15-09-2008 1400 debit 500.00 3
123 21-09-2008 1530 debit 100.00 4
65 22-09-2008 1645 credit 100.00 5
123 02-09-2008 1744 credit 500.00 6
17 07-09-2008 2300 debit 100.00 7

------------------------The customers.txt is like
this------------------------------------------------
Account Id = 123
Name = Matt Damon
Address = 465 Ripley Boulevard, Oscar Mansion
DOB = 10-10-1970
Phone Number = 790-3233
Account Balance = 405600.00
Account Type = Fixed
Fixed Daily Interest = 0.05

Account Id = 126
Name = Ben Affleck
Address = 200 Hunting Street
DOB = 25-10-1968
Phone Number = 432-4579
Account Balance = 530045.00
Account Type = Saving

Account Id = 65
Name = Salma Hayek
Address = 45 Mexican Boulevard, Hotel California
DOB = 06-04-73
Phone Number = 790-0000
Account Balance = 2345.00
Account Type = Checking

--------------------------------------------------------------------------------------------------

I hope the above information is sufficent to tell you what my program
want to do.