Java Interfaces

dave13

HEy. I have an interface class called EmployeeObserver and i have an Employee Class that implements this.I get this error message.
Employee.java:4: Employee is not abstract and does not override abstract method
equals() in EmployeeObserver
Equals is declared as a boolean in the interface and is defined in the class.It worked fine until i added the interface.
Anyone have any idea how to get round this?
Cheers

OfflerCrocGod

At a guess you have a problem with the way you implemented equals(). In the interface it's probably different....you may not be actually implemeting what you have in the interface. Post the code and it may become clearer.

GreeBo

wonderboy wrote:

HEy. I have an interface class called EmployeeObserver and i have an Employee Class that implements this.I get this error message.
Employee.java:4: Employee is not abstract and does not override abstract method
equals() in EmployeeObserver
Equals is declared as a boolean in the interface and is defined in the class.It worked fine until i added the interface.
Anyone have any idea how to get round this?
Cheers

check that your signatures match
i.e if your interface takes in two Employee objects but your Employee:equals() method takes in two Strings.

Post some code and we will spot it for ya straight away.

Draupnir

CA4 Wonderboy? OO Software Patterns project?

dave13

Here's a segment of the employee class including the equals method
import java.io.Serializable;

public class Employee implements Cloneable, Serializable, EmployeeObserver
{
public boolean equals(Object o)//Overrides the equals operator
{
if(o==null)
{
return false;
}

Employee em;
try{
em = (Employee)o;
}
catch(ClassCastException e){
return false;
}
if(name.equals(em.name))
{
return true;
}
return false;
}
}

And heres the interface
public interface EmployeeObserver
{
void receive();
Object clone();
boolean equals();
}
And yes CA4. This is all thats holding me up
Any advice appreciated

OfflerCrocGod

Firstly use generics, secondly in the interface Object o is missing boolean equals(Object o); should work. Try it.

Hobbes

Also shouldn't it be...

public boolean equals(Object o);

Also do any of the other interfaces implement the equals(Object o) method?

HaVoC

OfflerCrocGod wrote:

Firstly use generics, secondly in the interface Object o is missing boolean equals(Object o); should work. Try it.

generics are only available in java 1.5, your college may not have it installed as its fairly new.

Enygma

Everthing in an interface is implicitly public anyway so it doesn't really matter.
The other interfaces are just markers, they don't declare any methods.

OfflerCrocGod

HaVoC wrote:

generics are only available in java 1.5, your college may not have it installed as its fairly new.

I know so you just install it. All my code is Java 5, God I love Generics and I really don't care what the college uses, do your own stuff.

halenger

Gotta love this project. *cries*

Painful... Scrapped my code twice now I think it is and moving onto a 3rd attempt. Overcomplicating this everytime. Think I've an idea now but looking for a suitable pattern.

GreeBo

OfflerCrocGod wrote:

Firstly use generics

*IF* you are using jdk 1.5+
also, how would Generics help in this case?

dave13

Thanks for the help.Got it working.H
Home and dry(I think).

OfflerCrocGod

GreeBo wrote:

also, how would Generics help in this case?

It's just better/nicer all this "Object" crap is horrid.

Stark

Yeah you don't have to do casting and type checking is done at compile time rather than runtime so "Classcastexceptions" will be a thing of the past.

HaVoC

It just some lectures bitch over using a differant jdk then class happened to a friend of mine he used 1.4 and college was 1.3 he used a 1.4 feature that made the assignment easier and he only got 50%. but sense your a 4th year u shouldnt get that crap.

GreeBo

OfflerCrocGod wrote:

It's just better/nicer all this "Object" crap is horrid.

Yeah, but how do Generics help you to override the equals method?