Thread: Address Book Program Issues

Thanks your being a great help

Still having this issue with my addEntry() method

It compiles fine, but when i finish entering the last piece of data i get an error
and the line of code is -

"java.lang.String.NullPointerException: null"

list[top] = entry;

Looking back at what you said about this:

The TextUI class needs a reference to the AddressBook object that the addEntry method can use to call a method in the AddressBook class to add the entry the addEntry method has created.

I need to create a method inside of AddressBook that is called by the addEntry method.
And the method inside the AddressBook class - function is to create an entry

Is that right?

What variable is null? Make sure you give the variable a valid value before you use it.

I thought you had your design done and were now ready to code the program.
Look back through the posts to see what you decided to do where and when. Then do that.

Before you do any more coding you need to get a design for the program. What parts of the program do what and store what.

My AddressBook class needs to hold a collection of contacts.
So in my addressbook class i need to be able to create contact object and in an array.
These contact object need to be the entry that i'm using here
so the contact object is created stored in addressbook.

AddressBook entry = new AddressBook();
    list[top] = entry;
    top++;

This is in addressbook class

public AddressBook()
    {
        list = new Contact[MAXENTRIES];
    }

that i believe makes contact an arraylist with maxentries being the most amount of contacts allowed in the addressbook and list being the name of the arraylist

I'm living in Missouri, a state famous for its mules.

I was more focussed on getting this sorted for tomorrow tbh and then spend the time to go through and thank every single post.

Sorry i'm not use to forums i didn't realise the button meant so much, but i have said during how much i appreciated the time and the help and i'm sorry i'm a pain in the ass with all this stuff i don't like asking so many things and don't want to waste peoples time but i really need the help to finish this before tomorrow or i'm screwed

So i've finally sorted out my AddressBook class i think and still sorting out the addEntry method in the Textui

Having two issues, 1st the try{ is an unreachable statement and i can't figure out why
2nd is the

Contact contact = new Contact(name, address);

i need to make a contact out of all that information but still not sure how

public void addEntry()
        {
 
            System.out.println("Enter Contact Details: ");
            String forename = "";
            String surname = "";
            String street = "";
            String city = "";
            String county = "";
            String country = "";
            String post = "";
 
 
           if(addressbook.isFull())
                System.out.println("Address Book is full");
                return;
 
            //asks the user for the data of the address book
            try{
                System.out.print("Forename: ");
                forename = keyIn.readLine();
                System.out.print("Surname: ");
                surname = keyIn.readLine();
                System.out.print("Street: ");
                street = keyIn.readLine();
                System.out.print("City: ");
                city = keyIn.readLine();
                System.out.print("County: ");
                county = keyIn.readLine();
                System.out.print("Country: ");
                country = keyIn.readLine();
                System.out.print("Postcode: ");
                post = keyIn.readLine();
 
            }catch(Exception e){
                System.out.println(e);
                System.exit(0);
            }
            Name name = new Name(forename, surname);
            Postcode postcode = new Postcode(post);
            Address address = new Address(street, city, county, country);
 
            Contact contact = new Contact(name, address);
            addressbook.addContact(contact);
        }

The problem is the code is indented but it's missing the {}s.
ALWAYS code the starting { and the ending } down one line when coding an if statement. Start with this and THEN fill in the code inside of the {}s

   if(some condition) {
 
   }

thanks,

now onto show all entries:

In my Contact class

public void showContact(Contact contact)
        {
             for( int index = 0; index < top; index++)
                {
                    System.out.println((index+1)+" Forename:"+
                    list[index].toString());
                    System.out.println((index+1)+" Surname:"+
                    list[index].toString());
                    System.out.println((index+1)+" Street:"+
                    list[index].toString());
                    System.out.println((index+1)+" City:"+
                    list[index].toString());
                    System.out.println((index+1)+" County:"+
                    list[index].toString());
                    System.out.println((index+1)+" Country:"+
                    list[index].toString());
                    System.out.println((index+1)+" Postcode:"+
                    list[index].toString());
                }
        }

In my AddressTextUi Class:

public void viewEntries(){
              //checks if the address book is empty
              if(addressbook.isFull()){
                System.out.println("Address Book is full");
                return;
            }
            addressbook.showContact(contact);
 
       }

It can't find the constructor for Contact and i put

Name name = new Name(forename, surname);
            Postcode postcode = new Postcode(post);
            Address address = new Address(street, city, county, country);
            Contact contact = new Contact(name, address);

It can't find the variables so do i have to list them all again?

oops good point.

Added to Address class:

boolean isEmpty() {
            return top = 0;
           }

However it expects int so if i use

int isEmpty() {
            return top = 0;
           }

Then it compiles in Address Class but in my textui

   public void viewEntries(){
             if(addressbook.isEmpty()){
                System.out.println("Address Book is full");
                return;
            }
       }

It has error message - "incompatible types - found int but expected boolean"

Use = to assign a value to a variable. An assignment returns the value (and type) of the left hand operand.
Use == to compare two operands. It returns a boolean value.

Damn of course i missed it.

So now

public void viewEntries(){
             if(addressbook.isEmpty()){
                System.out.println("Address Book is full");
                return;
            }
 
            Contact contact = new Contact(name, address);
            addressbook.viewContact(contact);
 
       }

However it can't find variable name and address.

However it can't find variable name and address.

where is it looking?

I think it's looking at the Contact class:

 public class Contact
{
    private Address address;   
    private Name name;
 
 
    public Contact(Name name, Address address)  
    {  
        this.name = name;
        this.address = address;
    }     
 
    @Override  
    public boolean equals(Object obj) {  
        if (this == obj)  
            return true;  
        if (obj == null)  
            return false;  
        if (getClass() != obj.getClass())  
            return false;  
        Contact other = (Contact) obj;  
        if (address == null) {  
            if (other.address != null)  
                return false;  
        } else if (!address.equals(other.address))  
            return false;  
 
        if (name == null) {  
            if (other.name != null)  
                return false;  
        } else if (!name.equals(other.name))  
            return false;  
        return true;  
    }  
 
    @Override  
    public String toString() {  
        return super.toString() + "\n" + address + "\n" + name + "\n";  
    }  
}

i don't think my AddressBook class declares a new contact

Should it?

This just declares a Contact arraylist doesn't it , if its pointing at Contact class it shouldnt matter should it as if its declared in AddressBook it would be the same i think as it would be the name and address

public class AddressBook
{
    //index of the last entry
    private int top = 0;
   //constant number that indicates the maximum
   //number of entries in the address book
   private static final int MAXENTRIES = 5;
  //array of Address Book Entries
   private Contact[] list;
 
    /**
     * Constructor for objects of class AddressBook
     */
        public AddressBook()
        {
        list = new Contact[MAXENTRIES];
    }
 
 
     public Contact getContact(int n)
     {
         if(n >= top)
            return null;
            return list[n];
     }
 
     public void addContact(Contact contact)
        {
          if(top == MAXENTRIES)
           throw new IllegalStateException("The Addressbook is full");
          list[top++] = contact;
        }
 
      public void removeContact(Contact contact)
        {
          if(top == MAXENTRIES)
           throw new IllegalStateException("The Addressbook is full");
          list[top--] = contact;
        }
 
        public void viewContact(Contact contact)
        {
             for( int index = 0; index < top; index++)
                {
                    System.out.println((index+1)+" Forename:"+
                    list[index].toString());
                    System.out.println((index+1)+" Surname:"+
                    list[index].toString());
                    System.out.println((index+1)+" Street:"+
                    list[index].toString());
                    System.out.println((index+1)+" City:"+
                    list[index].toString());
                    System.out.println((index+1)+" County:"+
                    list[index].toString());
                    System.out.println((index+1)+" Country:"+
                    list[index].toString());
                    System.out.println((index+1)+" Postcode:"+
                    list[index].toString());
 
                }
        }
 
        boolean isFull() 
         {
             return top == MAXENTRIES;
         }
 
        boolean isEmpty() 
        {
           return top == 0;
        }
}

This just declares a Contact arraylist doesn't it ,

You have posted what looks like the definition for the AddressBook class.
What is the "this" you refer to?
Also where is the arraylist? I see an array but no arraylist.

it would be the same i think as it would be the name and address

I have no idea what you are talking about here.