CODEWITHSUNDEEP
javagenerics
Chris Cashwell
Chris Cashwell

Reputation: 22859

Default Generic Type

Say I have the following generic class:

public class Foo<T extends Bar> {
   // stuff
}

Is it possible to specify a default type(Baz, for instance), which would act as T if no T were passed in?

Upvotes: 4

Views: 2360

Answers (2)

jdevelop
jdevelop

Reputation: 12296

Use factory method like

public <T extends Bar> static Foo<T> getInstance(Class<T> clz) { 
    if (clz == null) 
        return new Foo<Bar>; 
    else 
        return clz.newInstance();
}

Upvotes: 2

Andy Thomas
Andy Thomas

Reputation: 86391

No. See "Type Variables" in the Java Language Specification.

That said, you can provide subclasses which accomplish a similar purpose:

public class Foo<T extends Bar> { ... }

public class FooDefault extends Foo< Baz > { ... }

Upvotes: 3

Related Questions