Stumped, need inspiration.

[Jesse Crockett]

Please glance over the following code. It is basically just a skeleton at about 1/3 complete. I am to give the Customer class additional functionality to handle multiple accounts, for which I can think of no better than an int[10] array at new construction. And then I am to supply functionality for customers with shared accounts. Helpful suggestions are greatly appreciated.

edit: I know that it says Midterm and that it's obviously homework, but i've dropped the course and the professor is giving me a chance to get a waiver for the course if i do all this work. i am not asking anybody to do all the work, just point the right direction. believe me, i'd rather be programming Swing. :-)

 
import java.util.*;
 
public class Midterm {

public static void main(String[] args) {
new BankTest();
}
 
} // end Midterm
 
 
abstract class Account {
 
private int accountNumber;
private double currentBalance;

public abstract void deposit(int acct, double amt);
public abstract void withdraw(int acct, double amt);
 
} // end Account
 
 
class SavingsAccount extends Account {

private double interestRate;

SavingsAccount(int accountNumber, double initialFunds, double acctInterestRate) {
interestRate = acctInterestRate;
this.accountNumber = accountNumber;
currentBalance = initialFunds;
}

void deposit(int acct, double amt) {
currentBalance += amt;
}

void withdraw(int acct, double amt) {
currentBalance -= amt;
}

void setRate(double rate) {
interestRate = rate;
}

double getRate(int acct) {
return interestRate;
}
 
} // end SavingsAccount
 
 
class CheckingAccount extends Account {
 
private double overdraftProtectionAmount;

CheckingAccount(int accountNumber, double initialFunds, double overdraftProtectionAmount) {
this.accountNumber = accountNumber;
balance = initialFunds;
this.overdraftProtectionAmount = overdraftProtectionAmount;
}

void deposit(int acct, double amt) {
currentBalance += amt;
}

void withdraw(int acct, double amt) {
currentBalance -= amt;
}

void setOverdraftProtectionAmt(double amt) {
overdraftProtectionAmount = amt;
}

double getOverdraftProtectionAmount() {
return overdraftProtectionAmount;
}
 
} // end CheckingAccount
 
 
class Customer {
 
private String name;
private int customerID;
private boolean hasAccount = false;
private int[] accounts;

Customer(String name, int id) {
if(!hasAccount) {
accounts = new int[10];
hasAccount = true;
}

this.name = name;
customerID = id;
}

void setName(String name) {
this.name = name;
}

String getName() {
return name;
}

void setID(int id) {
customerID = id;
}

int getID() {
return customerID;
}

[B]// account array functionality

// joint account functionality[/B]
 
} // end Customer
 
 
class BankTest {
 
 
 
} // end BankTest    

[ December 09, 2006: Message edited by: Jesse Crockett ]

[Jeroen T Wenting]

Why an array? Far better to use a List or Set of accounts.
But do you really want such a close tie between Customer and Account.
As you indicate you want shared accounts it might be better to have another way of mapping them, like a Bank class which holds a Map of Customers with a List or Set of Accounts per customer.

[Jesse Crockett]

The Prof specifies "an array of accounts" but no more than that. I don't know about Lists and Sets. I'm still looking at this code and going nowhere. It is really frustrating. Now I can see that the Customer constructor is flawed.

[Craig Wood]

int[] is the type for an array of ints. An array of Accounts would have the type Account[].
Since both type of accounts have a common superclass you might be able to group both
account types in the same data structure; you just have to play around with it and see how
to make it do what you want.
As far as the arrays, you can open the account with a zero–length array of accounts
and add each new account to this array as they arrive. For example, say I have an array of
Rectangles named "rects" and I want to add another Rectangle to it. I could make a
method in which I could do this:

Rectangle[] temp = new Rectangle[rects.length+1];
System.arraycopy(rects, 0, temp, 0, rects.length);
temp[rects.length] = myLatestRectangle;
rects = temp;

[Jesse Crockett]

I am trying to make a piecemeal that will get a passing mark --- just trying to get something to turn in. Right now I am confused by the errors pertaining to my use of references "ca" and "ca1" right after the for loop in the BankTest constructor:

 
jess@linux:~/java$ javac BankTest.java
BankTest.java:85: variable ca might not have been initialized
                        ca.deposit(customers[1].accounts[1], ca1.currentBalance);
                        ^
BankTest.java:85: variable ca1 might not have been initialized
                        ca.deposit(customers[1].accounts[1], ca1.currentBalance);
                                                             ^
2 errors
   

 import java.util.Scanner;
 
public class BankTest {

String name;
int id;
int acctNumber;


BankTest() {
 
 SavingsAccount sa;
 CheckingAccount ca, ca1;
 
 Scanner console = new Scanner(System.in);

Customer[] customers = new Customer[3];

for(int i = 0, j = 0; i < 3; i++) {
System.out.print("enter customer name: ");
name = console.next();
 
System.out.print("enter customer bank ID: ");
id = console.nextInt();

customers[i] = new Customer(name, id);

switch (i) {

case 0: 

{

System.out.println(name + " is opening a savings account with $1000 at 2% interest");
System.out.print("enter account number: ");
acctNumber = console.nextInt();

customers[i].accounts[j] = acctNumber;

sa = new SavingsAccount(acctNumber, 1000, 2.0);
System.out.println(sa);
break;
}

case 1:

{
System.out.println(name + " is opening a checking account with $5000 plus $100 overdraft protection credit");
System.out.print("enter account number: ");
acctNumber = console.nextInt();

customers[i].accounts[j] = acctNumber;

ca = new CheckingAccount(acctNumber, 5000, 100);
System.out.println(ca);
break;
}

case 2:

{
System.out.println(name + " is opening a checking account with $4000 plus $100 overdraft protection credit");
System.out.print("enter account number: ");
acctNumber = console.nextInt();


customers[i].accounts[j] = acctNumber;

ca1 = new CheckingAccount(acctNumber, 4000, 100);
System.out.println(ca1);
break;
}


     }// end switch
  }// end for loop
  
  // make joint account
  
  System.out.println("Customers " + customers[1].name + " and " + customers[2].name
  + " are creating a joint account...");

ca.deposit(customers[1].accounts[1], ca1.currentBalance);
ca.setOverdraftProtectionAmt(ca.getOverdraftProtectionAmount() + ca1.getOverdraftProtectionAmount());
ca1.accountNumber = ca.accountNumber;

System.out.println(customers[1].name + " and " + customers[2].name
+ " now have a joint account, details: \n"
+ ca + "\n" + ca1);

  
 }// end constructor()

public static void main(String[] args) {
new BankTest();
}
 
} // end BankTest
 
 
abstract class Account {
 
int accountNumber;
double currentBalance;

abstract void deposit(int acct, double amt);
abstract void withdraw(int acct, double amt);
 
} // end Account
 
 
class SavingsAccount extends Account {

double interestRate;

SavingsAccount(int accountNumber, double initialFunds, double acctInterestRate) {
interestRate = acctInterestRate;
this.accountNumber = accountNumber;
currentBalance = initialFunds;
}

void deposit(int acct, double amt) {
currentBalance += amt;
}

void withdraw(int acct, double amt) {
currentBalance -= amt;
}

void setRate(double rate) {
interestRate = rate;
}

double getRate(int acct) {
return interestRate;
}

public String toString() {
return "Savings account #" + accountNumber + ", with " + currentBalance
+ ", at " + interestRate + " interest.\n";

}

} // end SavingsAccount
 
 
class CheckingAccount extends Account {
 
private double overdraftProtectionAmount;

CheckingAccount(int accountNumber, double initialFunds, double overdraftProtectionAmount) {
this.accountNumber = accountNumber;
currentBalance = initialFunds;
this.overdraftProtectionAmount = overdraftProtectionAmount;
}

void deposit(int acct, double amt) {
currentBalance += amt;
}

void withdraw(int acct, double amt) {
currentBalance -= amt;
}

void setOverdraftProtectionAmt(double amt) {
overdraftProtectionAmount = amt;
}

double getOverdraftProtectionAmount() {
return overdraftProtectionAmount;
}

public String toString() {
return "Checking account #" + accountNumber + ", with " + currentBalance
+ " and " + overdraftProtectionAmount + " overdraft credit.\n";

}
} // end CheckingAccount
 
 
class Customer {
 
String name;
int customerID;
int[] accounts;

{ 
accounts = new int[10];
for(int i = 0; i < 10; i++)
accounts[i] = 0;
 
}

Customer(String name, int id) {
this.name = name;
customerID = id;
}

void setName(String name) {
this.name = name;
}

String getName() {
return name;
}

void setID(int id) {
customerID = id;
}

int getID() {
return customerID;
}

// account array functionality
 

// joint account functionality
 
} // end Customer
 
 
 
   

[ December 09, 2006: Message edited by: Jesse Crockett ]

[Ulf Dittmer]

Fields that are defined inside of a method (like sa, ca and ca1) need to be initialized before they are used, and the compiler needs to be sure of that. Note that it doesn't complain about sa, because that is definitely initialized before it is used, but ca and ca1 are used in spots where they have not necessarily been initialized (e.g., if the switch took case 0).

The solution is to assign them something, e.g. null.
[ December 09, 2006: Message edited by: Ulf Dittmer ]