Java: constructor and argument list error

1
votes

I have this problem :

I am trying to compile this :

public class Agora extends CreditCardPayment {

public void run() {

CashPayment ad1 = new CashPayment(12f);
ad1.paymentDetails();

CashPayment ad2 = new CashPayment(156.4f);
ad2.paymentDetails();

int cardnum1 = 1253462136;
CreditCardPayment ad3 = new CreditCardPayment(325.99f , "Visa" , "12/1/2015" , cardnum1);
ad3.paymentDetails();

int cardnum2 = 1235623151;
CreditCardPayment ad4 = new CreditCardPayment(999.99f , "Master" , "25/6/2016" , cardnum2);
ad4.paymentDetails();
 }
}

but it keeps giving me this error :

Agora.java:3: error: constructor CreditCardPayment in class CreditCardPayment cannot be applied to given types; public class Agora extends CreditCardPayment {

required: float,String,String,int found: no arguments reason: actual and formal argument lists differ in length

And this is the CreditCardPayment class :

public class CreditCardPayment extends Payment{

public CreditCardPayment(float x ,String name , String exp_date , int card_num) {
 super (x);
 Card_name = name;
 Expiration_date = exp_date;
 Card_number = card_num;
 }

public String paymentDetails() {
  return super.paymentDetails() + "Card's name :" + Card_name + " , Expiration Date :" + Expiration_date + " , Card Number :" + Card_number ;
  }

  private String Card_name;
  private String Expiration_date;
  private int Card_number;
  }

I am a computer science student and don't know much yet so please excuse me if this is just a silly mistake but I can't find it. Any help will be appreciated !

2
java
Try recompiling the classes. – Christian
Inheritance is a is-a relationship. When you create a Agora it also must create a CreditCardPayment. Since you need to pass arguments to the CreditCardPayment constructor, you need to use super() similar to how it is used in CreditCardPayment – clcto

2 Answers

1
votes

Building on @clcto's comment: Java provides a no-argument default constructor for classes unless you specify one or more other constructors. You have provided constructors for CreditCardPayment, so there is no no-arg constructor for this class.

You have not provided constructors for Agora, so the default behaviour is to assume a no-arg constructor, as if you had written

public Agora() {
    super();
}

But there is no no-arg constructor for the superclass (CreditCardPayment), so this fails.

0
votes

For some reason you are creating your Agora class as a subclass of CreditCardPayment. Because you haven't supplied a constructor for Agora, the default constructor is supplied by the compiler, which attempts to call the default constructor for the superclass, CreditCardPayment(). But no such constructor exists; the only constructor for CreditCardPayment takes 4 parameters. That explains the compiler error.

Your Agora class seems to use CreditCardPayment; it is not itself a CreditCardPayment. The relationship is "uses", not "is a". Agora uses CreditCardPayment, but Agora isn't a CreditCardPayment.

I would remove the extends CreditCardPayment clause on your Agora class definition; it's not needed and it shouldn't be there.

public class Agora {