Generic Question

[Akhil Maharaj]

Fellow Ranchers ,

Can you explain

method1 and method2 - do they provide same functionality ?

method3 and method 4 - do they provide same functionality ?
Line 3 gives compile error

can anybody explaing line1 - line please ?

 import java.util.*;
 
class GenericClasses_2
{
 

 <E extends Animal> void method1(List<E> e) {   }                           // Line 1
 
                    void method2(List<? extends Animal> e) {   }            // Line 2
 
 // <E super Animal> void method3(List<E> e) {   }      // compile error    // Line 3
 
  void method4(List<? super Animal> e) {  }                                 // Line 4
}
 

class Animal{  }
 
class Dog extends Animal {  }
 
class Alsatian extends Dog { }   

[Akhil Maharaj]

All ,

I think I found the answer at
http://www.angelikalanger.com/GenericsFAQ/FAQSections/TypeArguments.html#FAQ203

Line 1 and Line 2 are same.
Line 3 Is not allowed by compiler . Type parameters Can not have lower bound .

Line 4 is same as Line 1 . Except that You can add Animals to List
(This we all know ).

The major question was Line 3 . I think I have to sink in the fact that Type parameters Can not have lower bound .

Any more ideas are welcome