Generics refresher

[Hussein Baghdadi]

Hi,
In Java Generics, type conversion is based on the base type, not the parameters to that type.
Why this code is failing?

List<Integer> ints = new LinkedList<Integer>();
List<Number> nums = ints;

Conversion is based on List and LinkedList, not on Integer and Number.
Thanks.

[Henry Wong]

Think about what would happen if the compiler allowed the assignment.

If the assignment was allowed....

List<Integer> ints = new LinkedList<Integer>();  
List<Number> nums = ints;         // Assume legal

nums.add(new Double(3.14));     // This, of course, is legal.

Then didn't I just put a double object into the ints list?

Henry

[Hussein Baghdadi]

So when Generics are involved, type conversion is based on the parameterized type (List, LinkedList) or on the parameter to the type (Integer, Number)?