Instantiating generic class in java?

Question

I am using Java1.7 and using generics.

I wrote a generic class as below.

 public class SomeCollection<T extends MyPojo<K>, K> {



    }

Now, how can i instantiate above class? I mean how can i create an instance for above class?

I am doing as: SomeCollection<MyPojoSubClass, SomeType> sss = new SomeCollection<>(); Compiler is not giving any error. IS it correct way ?

Thanks!

`SomeCollection,String>> collection = new SomeCollection<>();` assuming you have not made the default constructor private and you use a string as a "key" (K) - however - keys are usually used as the first generic type and should consist of an immutable class - else you won't be able to retrieve the value which belongs to the key. — Roman Vottner, Jan 09 '14 at 10:26
Replace T and K with your desired class. And create the object as usual you create in java — Rahul, Jan 09 '14 at 10:29
I am doing as: SomeCollection sss = new SomeCollection<>(); Compiler is not giving any error. IS it correct way ? — user755806, Jan 09 '14 at 10:39
only if MyPojoSubClass is defined like `class MyPojoSubClass extends MyPojo` — mvieghofer, Jan 09 '14 at 10:40

Eugene · Accepted Answer · 2014-01-09T10:31:34.633

3

new SomeCollection<MyPojo<String>, String>();

Or are we missing something?

edited Jan 09 '14 at 10:31

answered Jan 09 '14 at 10:29

Eugene

@user755806 yup it is correct. that is called the diamond operator and it is specific for java 7, it was made so that we do not type that much. – Eugene Jan 09 '14 at 10:42

1 Answers1