Re: Force a class to have certain static methods
Chris wrote:
I want to have these classes have certain static methods like getName()
and getDescription() that just return constants. The trouble is, you
can't put static methods in an interface. You also can't have static
abstract methods.
I could make these methods non-static, but then you'd have to actually
create each class just to get its description, and that's an expensive
process. The classes can contain data structures that are quite large.
What's the workaround?
I also find that some of Java's limitation on interfaces and abstract
classes just don't make a lot of sense. I have no direct solution for you.
One thought: have each class implement an empty interface just to "mark"
it as a type that supports your descriptions. However, since you can't
actually guarantee these constants exist, you'll have to tease them out
with reflection to avoid throwing an error.
Note that "getName" already exists in the Class object, if the class
name itself will do.
You might want to declare a class for your constants, just to reduce the
likelihood that a programmer will make a mistake.
final class DescriptionConstants {
private String name;
private String desc;
DescriptionConstants( String name, String desc ) {
this.name = name;
this.desc = desc;
}
public String getName() { return name; }
public String getDesc() { return desc; }
}
class RandomClass implements DescriptionIface {
private final DescriptionConstants myConsts
= new DescriptionConstants( "some name",
"hey how bout those constants?" );
static DescriptionConstants getDesc()
{ return myConsts; }
}
Not "constants" but much cheaper than instantiating a complex class, and
there's a little protection for the harried programmer.