I don't find where I did wrong ...

[allexif]

Hello! I'm currently learning java from a book and made this exercise, the withdraw() and deposit() methods doesn't work, some help please?

here is my code:

package Chapter8;

import java.util.*;

public class Ex8_7 {
	public static void main (String args[]){
		
		Account account = new Account(1122, 20000.0D);
		
		account.setAnnualInterestRate(4.5D);
		
		account.withdraw(2500.0D);
		
		account.deposit(3000.0D);
		
		System.out.print("The balance is "+account.getBalance()+"\n"+"The monthly interest rate is "+account.getMonthlyInterestRate()+"\n"
				+"The date when this account was created is: "+account.getDateCreated());
		
	}
}

class Account{
	
	private int id;
	private double balance;
	private double annualInterestRate;
	private Date dateCreated = new Date();
	
	Account(){
	}
	
	Account(int newID, double newBalance){
		id = newID;
		balance = newBalance;
	}
	
	public int getID(){
		return id;
	}
	
	public void setID(int newID){
		id = newID;
	}
	
	public double getBalance(){
		return balance;
	}
	
	public void setBalance(double newBalance){
		balance = newBalance;
	}
	
	public double getAnnualInterestRate(){
		return annualInterestRate;
	}
	
	public void setAnnualInterestRate(double newAnnualInterestRate){
		annualInterestRate = newAnnualInterestRate;
	}
	
	public String getDateCreated(){
		return dateCreated.toString();
	}
	
	public double getMonthlyInterestRate(){
		return Math.pow(1.0D+annualInterestRate, 1/12.0D) - 1.0D;
	}
	
	public double withdraw(double a){
		return balance - a;
	}
	
	public double deposit(double a){
		return balance + a;
	}
}

Thank you in advance!

[al_Marshy_1981]

Your deposit and withdraw methods do not change the value of balance. They merely return balance plus/minus the value passed to the methods

[allexif]

Can you please tell me if this is good? It's working ... And tell me if tere are other alternatives just for my knowledge.a


The new code:

package Chapter8;

import java.util.*;

public class Ex8_7 {
	public static void main (String args[]){
		
		Account account = new Account(1122, 20000.0D);
		
		account.setAnnualInterestRate(4.5D);
		
		account.withdraw(2500.0D);
		
		account.deposit(3000.0D);
		
		System.out.print("The balance is "+account.getBalance()+"\n"+"The monthly interest rate is "+account.getMonthlyInterestRate()+"\n"
				+"The date when this account was created is: "+account.getDateCreated());
		
	}
}

class Account{
	
	private int id;
	private double balance;
	private double annualInterestRate;
	private Date dateCreated = new Date();
	
	Account(int newID, double newBalance){
		id = newID;
		balance = newBalance;
	}
	
	public int getID(){
		return id;
	}
	
	public void setID(int newID){
		id = newID;
	}
	
	public double getBalance(){
		return balance;
	}
	
	public double setBalance(double newBalance){
		return balance = newBalance;
	}
	
	public double getAnnualInterestRate(){
		return annualInterestRate;
	}
	
	public void setAnnualInterestRate(double newAnnualInterestRate){
		annualInterestRate = newAnnualInterestRate;
	}
	
	public String getDateCreated(){
		return dateCreated.toString();
	}
	
	public double getMonthlyInterestRate(){
		return Math.pow(1.0D+annualInterestRate, 1/12.0D) - 1.0D;
	}
	
	public double withdraw(double a){
		return setBalance(balance-a);
	}
	
	public double deposit(double a){
		return setBalance(balance+a);
	}
}

[Danieldcc]

looks good to me....but why is there a setBalance method? makes the code more confusing to me. You also already have a getBalance method to return the balance, so the withdraw/deposit methods have no need to return anything. I would do it like this personally....

private void withdraw(double balance) {
this.balance = balance;
}

[allexif]

looks good to me....but why is there a setBalance method? makes the code more confusing to me. You also already have a getBalance method to return the balance, so the withdraw/deposit methods have no need to return anything. I would do it like this personally....

private void withdraw(double balance) {
this.balance = balance;
}

Yes, you're wright, but the "this." concept is explained in the next chapters so I didn't know about it ... I follow the book. Thank you very much! :)

Edit1: Oh, the withdraw and deposit methods must return the "balance - a" so is must be an expression there for the "+/-" operations wright?

[Danieldcc]

true, hung over so not sure what i was thinking

private void withdraw(double amount) {
balance = balance - amount;
}