Calculation returning 0.0

I'm having some issues with an assignment for my Java class. My calculation of numCredits * creditFee + addFee is not processing; it continues to return 0.0

The assignment:

(Note, I have not yet added the additional parts of the assignment, the adding and subtracting of 3 credit hours to RegistrationTester. I will add those once I figure out this problem.)

Here is a look at my code:

public class Registration {
//attributes
private String firstName = ""; 
private String lastName = "";
private double numCredits = 0;
private double addFee = 0;
private double creditFee = 70;
public double balance = 0;
//constructor
public Registration(String firstName, String lastName, double numCredits, double addFee){
this.firstName = firstName;
this.lastName = lastName;
this.numCredits = numCredits;
this.addFee = addFee;
}
public Registration(){} //
public void balance(double balance){
System.out.println(numCredits * creditFee + addFee);
}
public void addCredit(double addCredit){
if (this.balance > 0) {
this.balance = balance + addCredit * creditFee;
}
}
public void subCredit(double subCredit){
if (this.balance > 0){
this.balance = balance - (subCredit * creditFee);
}
}
//setters
public void setFirstName(String fname){
this.firstName = fname;
}
public void setLastName(String lname){
this.lastName = lname;
}
public void setNumCredits(double credits){
this.numCredits = credits;
}
public void setAddFee(double fee){
this.addFee = fee;
}
public void setcreditFee(double creditFee){
this.creditFee = 70;
}
public void setBalance(double balance){
this.balance = balance;
}
//getters
public String getFirstName(){
return this.firstName;
}
public String getLastName(){
return this.lastName;
}
public double getNumCredits(){
return this.numCredits;
}
public double getAddFee(){
return this.addFee;
}
public double getCreditFee(){
return this.creditFee;
}
public double getBalance(){
return this.balance;
}
}

and

public class RegistrationTester {
public static void main(String[] args){
Registration student1 = new Registration ("m", "w", 15, 60);
Registration student2 = new Registration ("d", "y", 12, 45);
//display students and their current stats
System.out.printf("%s %s:%n Current Credit Hours: %f%n Additional Fees: $%.2f%n"
+ "Current balance due: $ %.2f%n", 
student1.getFirstName(),student1.getLastName(), student1.getNumCredits(), student1.getAddFee(),
student1.getBalance());
System.out.printf("%s %s:%n Current Credit Hours: %f%n Additional Fees: $%.2f%n"
+ "Current balance due: $ %.2f%n", 
student2.getFirstName(), student2.getLastName(), student2.getNumCredits(), student2.getAddFee(),
student2.getBalance());        
}
}

Method 1: Properly setting balance

The balance always returns 0.0 because you never set the balance in your method.

I believe your balance method should be:

 public void balance(double balance){
this.balance=(numCredits * creditFee + addFee);
}

Method 2: Returning balance

You can replace student1.getBalance() in RegistrationTest.java with student1.balance() that returns a double.

RegistrationTest should be:

System.out.printf("%s %s:%n Current Credit Hours: %f%n Additional Fees: $%.2f%n"
+ "Current balance due: $ %.2f%n", 
student1.getFirstName(),student1.getLastName(), student1.getNumCredits(), student1.getAddFee(),
student1.balance());

And the method balance() should be:

 public double balance(){
return (numCredits * creditFee + addFee);
}

With these changes it outputs:

Mihail Dichev:
Current Credit Hours: 15.000000
Additional Fees: $60.00
Current balance due: $ 1110.00
Dene Logan:
Current Credit Hours: 12.000000
Additional Fees: $45.00
Current balance due: $ 885.00