CODEWITHSUNDEEP
javafilearrayliststringtokenizer
user3105072
user3105072

Reputation: 93

Write to Java ArrayList from text file giving me issues

My task is to extract all the records from a text file (which has 2 columns-name and manager name- and 9 rows), create an Employee object from each record ( name and manager), and then add the employee object to an ArrayList that accepts Employee objects.

For some reason, when I attempt to loop through the list later on, it seems as if the last record is what is being stored for all of the records.

Below is my code. I even put some print line statements to make sure that token was the correct name and manager name right before they get added, but again, when I loop through it afterwards all the records show up as "Veronica and Bob".

Here is the text file:

Betty     Sam
Bob       Sally
Dilbert   Nathan
Joseph    Sally
Nathan    Veronica
Sally   Veronica
Sam Joseph
Susan   Bob
Veronica

Here is my method:

List<Employee> employees = new ArrayList();

 public void loadData() throws FileNotFoundException, IOException {
    FileReader fr = new FileReader("C:\\Users\\jeff\\Documents\\NetBeansProjects\\Java3Project1\\src\\java3project1\\employee.txt");
    BufferedReader br = new BufferedReader(fr);
    String line;
    Employee e = new Employee();
    while ((line = br.readLine()) != null) {

        StringTokenizer st = new StringTokenizer(line);
        int counter = 0;
        while (st.hasMoreTokens()) {
            String token = st.nextToken();
            if (counter==0){
                e.setName(token);
                System.out.println("Name added: " + token);

            }
            if (counter == 1) {

                    e.setManager(token);
                    System.out.println("Manager set: " + token);
            }   
            employees.add(e);
            counter++;
        }//end while2
    }//end while1
} //end loadData()

When I check the list after this method was called, all the records come out as Name: Veronica Manager: Bob

I cant seem to figure out what I am doing wrong. All help is greatly appreciated. Let me know if you have any questions or need more clarification.

Thank you!

Upvotes: 0

Views: 57

Answers (2)

Mohammed Aouf Zouag
Mohammed Aouf Zouag

Reputation: 17132

All the employees in your arraylist refer to the same e instance that you create right before you start reading from the file, (They all share the same instance).

You need to change

Employee e = new Employee();
while ((line = br.readLine()) != null) {

to

while ((line = br.readLine()) != null) {
    Employee e = new Employee();

in order to create a new, separate instance for each Employee, before adding it to the arraylist.

EDIT:

You were adding a new employee at the end of each iteration of your inner loop (which runs twice), & that's why you were getting the records doubled.

while ((line = br.readLine()) != null) {
    Employee e = new Employee();
    StringTokenizer st = new StringTokenizer(line);
    int counter = 0;
    while (st.hasMoreTokens()) {
        String token = st.nextToken();
        if (counter==0){
            // Set the name
        }
        if (counter == 1) {
            // Set the manager
        }

        // employees.add(e); // Move this line from here
        counter++;
    }//end while2
    employees.add(e); // to here : the name & the manager are now both set
}//end while1

Upvotes: 2

Mark B
Mark B

Reputation: 200562

You are only creating an Employee object one time, at this line:

Employee e = new Employee();

Then you are just assigning a new name to that Employee object over and over, so in the end that object has the name of the last employee in your file. You need to be creating a new Employee object for each Employee you read in.

Upvotes: 1

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