java reflection

Question 1

What is the single meta-class called in java?

Answer 1

Class

Question 2

What is the difference between getMethods and getDeclaredMethods?

Answer 2

getMethods - only public methods but includes inherited methods (public).

getDeclaredMethods - all methods in the class but no inherited.

Question 3

How to invoke private methods with reflection?

Answer 3

1. use getDeclaredMethods
2. use m.setAccessible(true);
3. m.invoke()

Question 4

What’s the difference between reflection in java and reflection in C# or squeak?

Answer 4

in java Can’t add / modify fields (structure), methods (behavior)

Question 5

What’s missing in javas reflection?

Answer 5

Reflection is introspection only (unlike squeak
and C#)
– Can’t add / modify fields (structure), methods (behavior)
• Implementation is not available
– Program logic is not reflected (cannot change methods’
source code)
• Major performance impact
– Much slower then doing the same operations directly…
• Complex code