Generic syntax for extends or equal to

Question

How is the syntax in Java for GenericExample<ItemType (extends or equal to) Object>?

Thanks, Adam.

Update:

Thanks for all your replies. The answers here are more related to the use of the generics in code, I would like to discuss the deceleration implementation, for example:

class GenericExample<ItemType (extends or equal to) ParentType> { } class Inherited<ParentType> extends GenericExample<ParentType> { /* The type parameter in this class does not compile. I would like to find a work around to make something like this to work. I would like to have ParentType=JComponent , and thus to specify that the Inherited class uses JComponent for needed flexibility*/ }

I hope this makes more sense...

Adam.

I'm pretty sure that it's not possible in Java. If I understood it correctly, it's like when you in C# declare a "GenericExample< T > where T: SomeParentClass" — usr-local-ΕΨΗΕΛΩΝ
– usr-local-ΕΨΗΕΛΩΝ, Commented Jan 19, 2011 at 16:12
@djechelon: You would be wrong in thinking that it isn't possible. =) — ColinD
– ColinD, Commented Jan 19, 2011 at 17:19
I never use a single letter to refer to a parameter type, I always use a mining-full Type name, it makes it easier to keep track over what the object needs to do, or what it is. — TacB0sS
– TacB0sS, Commented Jan 20, 2011 at 11:17

Nicolas · Accepted Answer · 2011-01-19 16:12:21Z

4

You already got it:

GenericExample<ItemType extends MyObject>

A first guide on generics can be found here: http://download.oracle.com/javase/1.5.0/docs/guide/language/generics.html

answered Jan 19, 2011 at 16:12

Nicolas

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3 Comments

rfeak Over a year ago

shouldn't that at least include a Generic parameter? Like: GenericExample<T extends MyObject> . Still bumping, as I think you have provided what the OP needed.

Nicolas Over a year ago

ItemType is a generic parameter. But you are right, in Java, common usage is to use One letter (ususally T) for generic parameter.

LINEMAN78 Over a year ago

Also remember that this is only enforced at compile time and will be replaced with type casts at runtime due to type erasure in Java.

GriffeyDog · Accepted Answer · 2011-01-19 16:48:17Z

1

GenericExample<T extends Object>

edited Jan 19, 2011 at 16:48

answered Jan 19, 2011 at 16:13

GriffeyDog

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1 Comment

ColinD Over a year ago

You are correct here, but I think it's more clear if you use some type other than Object as the type bound, since what you show here is equivalent to just GenericExample<T>.

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