java class inheritence
When class A **extends** class B

A can has more properties than B, what about class A **extracted from** class B. then class A 

can only has a subset of properties of class B.

I think this will be useful in some cases.

java class inheritence
===

When class A **extends** class B

A can has more properties than B, what about class A **extracted from** class B. then class A 

can only has a subset of properties of class B.

I think this will be useful in some cases.
