Java: Trying to read in a date into a constructor method

[davestar_delux]

Em as title really... i'm trying to run this constrctor object so that a date is passed to it from another object eventually and then it can store the date information in the appropriate format but I can't seem to get it to work, here is the code:

public class Customer
{
// instance variables
private String name;
private String address;
private Date dateOfBirth;

/**
* Constructor for objects of class Customer
*/
public Customer(String customerName, String customerAddress, Date customerDateOfBirth)
{
// add new customer

SimpleDateFormat formatter = new SimpleDateFormat("dd/MM/yyyy");
Date dateOfBirth = new Date();

name = customerName;
address = customerAddress;
dateOfBirth = customerDateOfBirth();
}

 

[Eriedor]

snip

I have never coded java but I do code c# which is quite similar.

Firstly, ocrrect me if im wrong but here you are redeclaring the variable dateofbirth in the local scope:

Date dateOfBirth = new Date()

I would imagine it would be:

dateOfBirth = new Date()

Secondly you create a formatting object for the date but don't use it, are you not supposed to pass it into the date constructor?

Finally customerdateofbirth is a variable not a method, remove the ().

 

[fezster]

You dont need to format the date till you use it. If you want to, then you could store the date formatted as a string, but that would be poor design. You have it basically right, with the following corrections:

public Customer(String customerName, String customerAddress, Date customerDateOfBirth)
{
// add new customer

name = customerName;
address = customerAddress;
dateOfBirth = customerDateOfBirth;
}

No need to declare a local dateOfBirth variable, as it already exists within the class. Also note the removal of () in the assignment, which would attempt to locate a method called customerDateOfBirth().

Also, if you intend to modify the original date object and dont want to modify the date object in this class, then you should use:

dateOfBirth = customerDateOfBirth.clone();

which would create a new copy of this Date object.

 

[davestar_delux]

Right I think I have the class working but I am struggling to test it as when I create an instance it asks to enter the parameters which i do but it throws up errors. I think they are due to the date, is there anyway I can test it quickly in this way? and if so, how do I enter the date?

 

[happytechie]

just create a second constructor that doesn't use a date parameter and use Date.today() or something

Paul

 

[fezster]

Use:

Customer c = new Customer("name", "address", new Date());

This will initialise it with todays date.

 

[davestar_delux]

Thanks guys. Another problem now, I have created this method:

public boolean updateOverdraftLimit(int newLimit)
{
//add code to check whether newLimit is between acceptable limits
overdraftLimit = newLimit;

System.out.println("New overdraft limit: £" + overdraftLimit);
return true;
}

And call it from another class like so:

SavingsAccount savAcc1 = new SavingsAccount();

savAcc1.updateOverdraftLimit(250);

How do I now use the return boolean value in the calling class to write out whether the update was successful or not?

 

[Eriedor]

if (savAcc1.updateOverdraftLimit(250))
{
     //do something
}

 

[davestar_delux]

Thanks for all the help so far everyone, i'm getting my head aorund a lot of this now. Sorry to be a pest but I have one more problem I could use help with.

I have to keep a log of transactions for my banking system, the only operations I need to perform on this are to add a transaction and to display all transactions so i've figured out I think my best option is a LinkedList which i'm fine with.

The trouble is there are 3 parts to each transaction which will need to be stored together, they are the transactionType (a string either withdraw or deposit), amount and the date. I don't know how to group these so that I can insert them into a single node on the list?

 

[Chrisss]

For each transaction create a new object which holds the 3 things you need to store, and then create a list of type <yourobject>

 

[davestar_delux]

Well I've created my object and it went okay, however when I try to pass parameters to put values into that object it is throwing up an error "java.lang.NullPointerException" and highlighting a line in my addTransaction method.

Here is the method calling it from my currentAccount class:

public boolean deposit(int depositAmount)
{
StringBuffer depositSB = new StringBuffer( "Deposit" );
trans1.addTransaction(depositSB, depositAmount);
System.out.println("Amount Deposited: £" + depositAmount);
return true;
}

And here is the full Transaction class that seems to have the error:


import java.util.*;
import java.text.*;
import java.util.LinkedList;

public class Transaction
{
class transactionTypeWrapper{
Date now;
StringBuffer transactionType;
int amount;
}

transactionTypeWrapper aTransaction;

public Transaction()
{
LinkedList transactions = new LinkedList();
}

public void addTransaction(StringBuffer transactionType, int amount)
{
aTransaction.transactionType = transactionType; //error appears to be with this line?
aTransaction.amount = amount;
System.out.println("Transaction Successful");
}
}

 

[Dj_Jestar]

dude.. this forum has

 tags for a reason..