Thread: Having trouble understanding object relationships and using them correctly?

I have an assignment where you need to transfer money from one account to the other account... using objects of course. So far I have three different files...but I'm getting a class/enum error.

import java.util.Scanner;
import java.text.NumberFormat;
 
public class accountTest{
 
 
	public static void main(String[] args){
		Scanner input = new Scanner(System.in);
		Scanner input2 = new Scanner(System.in);
		Scanner input3 = new Scanner(System.in);
		Scanner input4 = new Scanner(System.in);
		Scanner input5 = new Scanner(System.in);
		NumberFormat formatter = NumberFormat.getCurrencyInstance();
		System.out.println("Please enter your account balance: ");
		double balance = input.nextDouble();
		Account mark = new Account(balance);
		Account joe = new Account(500);
 
		System.out.println("Your account balance is: " + formatter.format(mark.getAccountBalance()));
 
		System.out.println("Please enter the amount you want to deposit into the account: ");
		double deposit = input2.nextDouble();
		System.out.println("The amount you are depositing is: " + formatter.format(deposit));
 
		mark.enterDeposit(deposit);
 
		System.out.println("Your account balance is: " + formatter.format(mark.getAccountBalance()));
 
		System.out.println("Please enter the amount you want to withdraw: ");
		double withdrawal = input3.nextDouble();
 
		System.out.println("The amount you are withdrawing is: " + formatter.format(withdrawal));
 
		mark.takeWithdrawal(withdrawal);
 
		System.out.println("Your account balance is: " + formatter.format(mark.getAccountBalance()));
 
		System.out.println("Please enter the amount you wish to transfer: ");
		double transferAmount = input4.nextDouble();
		System.out.println("Which account would you like to transfer " + formatter.format(transferAmount) + " to?");
		String account = input5.nextLine();
 
 
		Transaction trans = new Transaction(mark, joe);
		trans.transferMoney(transferAmount, account);
 
	System.out.println("You transfered " + transferAmount + " to " + account + ".");
 
			System.out.println("Mark's account balance is now " + formatter.format(mark.getAccountBalance()));
				System.out.println("Joe's account balance is now " + formatter.format(joe.getAccountBalance()));
 
 
 
	}
}

 
public class Account{
 
	private double balance = 0;
 
	public Account(double balance){
 
		this.balance = balance;
	}
 
 
	public double getAccountBalance(){
 
 
		return balance;
	}
 
	public double enterDeposit(double amount){
 
		balance = balance + amount;
 
 
			return balance;
	}
 
	public double takeWithdrawal(double amount){
		balance = balance - amount;
		return balance;
 
	}
 
}

 
public class Transaction{
 
 
	private Account mark;
	private Account joe;
	public Transaction(Account mark, Account joe){
 
	this.mark = mark;
	this.joe = joe;
 
 
 
	}
 
	public void transferMoney(double amount, String account){
 
 
		if(account == "joe")
		{
 
		 mark.takeWithdrawal(amount);
		 joe.enterDeposit(amount);
		}
 
		 else if(account == "mark"){
 
		 	joe.takeWithdrawal(amount);
		 	mark.enterDeposit(amount);
		 }
 
	}
 
 
	}

That's what I have so far... but I'm having trouble with the transaction class. When I tell it to deposit and withdraw it doesn't withdraw or deposit and the amounts in both accounts stay the same. Any help is appreciated!

Your problem is with comparing Strings:
if(account == "joe")
String are objects, therefore when you are comparing for equivalency, you need to use the .equals() method instead of ==
if(account.equals("joe"))

The "normal" way to compare two objects in java is to either:
1. override the .equals() method, in your Account class, that is inherited from the Object class
2. Implement the Comparable Interface (Comparable (Java Platform SE 6)) in your Account class.