Calculate total from list of lists and map to pojo

[Craig Star]

Hello,

I need to process my array list and calculate the total that is take from each account balance.
I can't have another data structure as per homework.

{
ArrayList<Customer> = {
{  Forename= Blue, Surname= Red, CustomerId= 2119954221, Age= 98, Accounts= [Account Name = Current Account, Account ID = 1, Accounts Balance = 0.0, Account total = 0.0, Account Name = Current Account, Account ID = 2, Accounts Balance = 0.0, Account total = 0.0] }
{Forename= Orange, Surname= Yellow, CustomerId= 1448877171, Age= 32, Accounts= [Account Name = Current Account, Account ID = 3, Account Balance = 10000.0, Account total = 10000.0, Account Name = Current Account, Account ID = 4, Account Balance = -100.0, Account total = -100.0, Account Name = Savings Account, Account ID = 26634, Account Balance = 10.0, Account total = 10.0] }
...................
}

POJO's

class Account {
    private final String accountName;
    private final int accountId;
    private final double accountBalance;
    private double accountTotal;
}

class Customer {
    private final String forename;
    private final String surname;
    private final long customerId;
    private final int age;
    private List<Account> accounts;
}

First though was to loop over the list and

public static void calculateAccountTotal(){
double total = 0;
        for (Customer c : CUSTOMERS) {
            for (Account a : c.getAccounts()) {
                total += a.getAccountBalance();
                a.setTotal(total);
            }
      }
}

This does not work as the previous total is added to the next customer.

A potential solution would be to add an accountKey to the Customer and Account, so I can have a constant in both lists, to check if they match and calculate the total.
Maybe that would stop the addition of balance to the next customer.
I don't think that is a go, tho.

Thank you for reading.

[Carey Brown]

What does it mean for an Account to have a total? Doesn't the balance represent the total? It seems like what you are looking for is a Customer total which is a total of all of the balances in all the accounts that the  customer has.

[Craig Star]

thank you, I understand now where I was wrong.
A customer is one and accounts are many.
Still, if I would have wanted to have a variable in each account, as "totalForAllAcounts", how would that be achievable?

customer: details
Account: details of the account + new field totalOfAllAccounts

I can solve the sew field in the customer.

[Dave Tolls]

Why would each Account have a total for all accounts?
That doesn't make much sense.

[Craig Star]

After some thought I understand.
If in any case there should be such a requirement, it would point a reference to the total in the Customer pojo