Reading from a text file and creating an array of objects Java

Question

I have these two classes: Contact and Phonebook:

public class Contact implements Comparable<Contact> {
    private String name;
    String[] numbers;
    private final int NUMBER_LIMIT = 5;
}

public class Phonebook {
    private final int CONTACT_LIMIT = 250;
    Contact[] contacts;
}

I want to transform the data from both classes to String and save it to a text file. For this purpose, I wrote the following functions:

public class Contact {

    @Override
    public String toString() {
        StringBuilder str = new StringBuilder();
        int len = numbers.length;

        str.append(name);
        str.append(System.lineSeparator());
        str.append(len);
        str.append(System.lineSeparator());

        for (int i = 0; i < len; i++) {
            str.append(numbers[i]);
            if (i != len - 1)
                str.append(System.lineSeparator());
        }

        return str.toString();
    }
}

public class Phonebook {
    @Override
    public String toString() {
        StringBuilder str = new StringBuilder();

        for (int i = 0, n = contacts.length; i < n; i++) {
            str.append(contacts[i].toString());
            if (i != n - 1) str.append(System.lineSeparator());
        }

        return str.toString();
    }

    public static boolean saveAsTextFile(Phonebook phonebook, String path) {
        boolean saved = true;
        PrintWriter toFile = null;
        try {
            toFile = new PrintWriter(new FileOutputStream(path));
            toFile.println(phonebook.toString());
        }
        catch (FileNotFoundException e) {
            saved = false;
        }
        finally {
            toFile.close();
        }
        return saved;
    }
}

The next step is reading the contents from an existing text file and recreating a Phonebook object. The text file has the following format:

Contact name (String)
Number of phone numbers (int)
Phonenumber(s) (String)

There can be more than 1 contact in the text file. So far I have this function for creating a contact from a string:

public static Contact valueOf(String s) throws InvalidFormatException {
        String lineSeparator = System.lineSeparator();
        String[] chunks = s.split(lineSeparator);
        int len = chunks.length;

        if (len < 2) throw new InvalidFormatException();

        //System.out.println(Arrays.toString(chunks));
        String name = chunks[0];
        String[] numbers = new String[Integer.parseInt(chunks[1])];
        for (int i = 2; i < len; i++)
            numbers[i - 2] = chunks[i];

        Contact contact = null;

        try {
            contact = new Contact(name, numbers);
            return contact;
        }
        catch (Exception e) {
            throw new InvalidFormatException();
        }
    }

And this one for creating the Phonebook(It is a work in progress):

public static Phonebook loadFromTextFile(String path) throws FileNotFoundException, InvalidFormatException {
    Scanner inputStream = new Scanner(new FileInputStream(path));
    ArrayList<String> contactInfo = new ArrayList<String>();
    int ctr = 0;
    int numContacts;
    String contactString = "";
    Contact contact = null;

    while (inputStream.hasNextLine()) {
        contactInfo.add(inputStream.nextLine());
        if (ctr == 1) {
            numContacts = Integer.parseInt(contactInfo.get(ctr));
            for (int j = 0; j < numContacts; j++) {
                contactInfo.add(inputStream.nextLine());
            }
            System.out.println("contactString inside while loop:");
            contactString = String.join(System.lineSeparator(), contactInfo);
            System.out.println(contactString);
            contact = Contact.valueOf(contactString);
            contactInfo.clear();
            System.out.println("contact inside while loop:");
            System.out.println(contact);
            ctr = 0;
        }
        ctr++;
    }

The problem I'm having is that this function works only for a single contact in the file. If there are multiple, it does not work. What am I doing wrong? My logic is this:

• Read line from text file and store it in ArrayList

• If you read the number of contacts:

  • Iterate over the number of contacts, reading every line and storing it in ArrayList

• When done, transform the contents of ArrayList to String, move it to contactString and call Contact.valueOf(String s). When I get this working, store the resulting Contact in a Contact[].

• Empty ArrayList and start again.

• Repeat until EOF

I cannot figure out what is causing the problem. Any help is appreciated.

Note : If it matters, this is a homework assignment.

EDIT: Sample .txt file:

John Doe
3
3124354353
1234324534
5768324242
Alice
1
0547623424
Bob
2
7863257643
3128443552

Answer 1

The problem seems to be the ctr variable.
It is initialized to 0

int ctr = 0;

incremented in the while loop

ctr++;

and there is an if statement in the while loop

if (ctr == 1) {

In there is also set to 0

So the while loop will execute twice, adding 2 lines to contactInfo then add another numOfContacts lines to contactInfo and then try to create a single contact.

Based on how the example text file looks like I would recommend this simpler version without the ctr variable

while (inputStream.hasNextLine()) {
    contactInfo.add(inputStream.nextLine());
    int numContacts = Integer.parseInt(inputStream.nextLine());

    for (int j = 0; j < numContacts; j++) {
        contactInfo.add(inputStream.nextLine());
    }
    System.out.println("contactString inside while loop:");
    String contactString = String.join(System.lineSeparator(), contactInfo);
    System.out.println(contactString);

    contactInfo.clear();
    System.out.println("contact inside while loop:");
}

Note that I defined contactString and numContacts in the loop as there is not reason for them to exist outside