CODEWITHSUNDEEP
javagenericswildcard
user467871
user467871

Reputation:

why Generic types only for Object?

What I mean is

interface A <T> {
}

class AImpl implements A < Integer > { // why not A< int >
}

I have read this article and googled it but still I have no idea why it is only for Object and not for primitive data types(int, void)?

Upvotes: 0

Views: 513

Answers (2)

Jack Cox
Jack Cox

Reputation: 3300

Generics don't work for int, float, boolean, etc. because primitive types do not have all of the associated metadata and structures that Object based types have. In Java primitive types are just that, primitive. All of that associated metadata enables things like generics, reflection, subclassing, etc.

Upvotes: 1

Jon Skeet
Jon Skeet

Reputation: 1500165

It's not just wildcards - Java generics simply don't support primitive types as type arguments at all.

See the Java Generics FAQ for more information about Java Generics in general, and this question in particular.

Upvotes: 3

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