Newbie Post: Question about Inheritance

[billelev]

Hi there,

I've tried to look into this issue but I'm having difficulty finding a solution.

I have two classes: PaymentDate and its subclass PaymentDateRef. PaymentDate has a method setMaturityPeri od that is called in the PaymentDate constructor, which ultimately sets the variable maturityPeriod.

In PaymentDateRef I have written a method setMaturityPeri od which I believed should override the superclass method of the same name.

Now, when I call the constructor of PaymentDateRef I must also reference the constructor of PaymentDate through the super keyword. However, what I am seeing is that this then calls setMaturityPeri od within PaymentDate and then from within the constructor of PaymentDateRef. ..i.e. the setMaturityPeri od method is called twice.

public PaymentDate() {
setMaturityPeri od();
}


public PaymentDateRef( ) {
super();
setMaturityPeri od();
}

Does anyone know how I can call setMaturityPeri od only once from within the constructor? I thought the override property would cause the new setMaturityPeri od to be called rather than the old, allowing the PaymentDateRef constructor to be used:

public PaymentDateRef( ) {
super();
}

but in this case only the original setMaturityPeri od method is called.

[dmjpro]

Hi there,

I've tried to look into this issue but I'm having difficulty finding a solution.

I have two classes: PaymentDate and its subclass PaymentDateRef. PaymentDate has a method setMaturityPeri od that is called in the PaymentDate constructor, which ultimately sets the variable maturityPeriod.

In PaymentDateRef I have written a method setMaturityPeri od which I believed should override the superclass method of the same name.

Now, when I call the constructor of PaymentDateRef I must also reference the constructor of PaymentDate through the super keyword. However, what I am seeing is that this then calls setMaturityPeri od within PaymentDate and then from within the constructor of PaymentDateRef. ..i.e. the setMaturityPeri od method is called twice.

public PaymentDate() {
setMaturityPeri od();
}


public PaymentDateRef( ) {
super();
setMaturityPeri od();
}

Does anyone know how I can call setMaturityPeri od only once from within the constructor? I thought the override property would cause the new setMaturityPeri od to be called rather than the old, allowing the PaymentDateRef constructor to be used:

public PaymentDateRef( ) {
super();
}

but in this case only the original setMaturityPeri od method is called.

Can you post the whole you written with code tags.
And what you need and what is wrong with you?

Kind regards,
Dmjpro.

[JosAH]

Hi there,

I've tried to look into this issue but I'm having difficulty finding a solution.

I have two classes: PaymentDate and its subclass PaymentDateRef. PaymentDate has a method setMaturityPeri od that is called in the PaymentDate constructor, which ultimately sets the variable maturityPeriod.

In PaymentDateRef I have written a method setMaturityPeri od which I believed should override the superclass method of the same name.

Now, when I call the constructor of PaymentDateRef I must also reference the constructor of PaymentDate through the super keyword. However, what I am seeing is that this then calls setMaturityPeri od within PaymentDate and then from within the constructor of PaymentDateRef. ..i.e. the setMaturityPeri od method is called twice.

public PaymentDate() {
setMaturityPeri od();
}


public PaymentDateRef( ) {
super();
setMaturityPeri od();
}

Does anyone know how I can call setMaturityPeri od only once from within the constructor? I thought the override property would cause the new setMaturityPeri od to be called rather than the old, allowing the PaymentDateRef constructor to be used:

public PaymentDateRef( ) {
super();
}

but in this case only the original setMaturityPeri od method is called.

If a ctor calls a method from its own class that is not private (either directly or
indirectly) it is a serious indication of bad design if that class is intended to be
extended by subclasses. In the Java Articles section there's an article about the
Liskov Substitution Principle. It is right on target w.r.t. your problem.

kind regards,

Jos