Generics what does <?> actually mean?
generics, java
Solution
`<?>` is a shorthand for `<? extends Object>`, it's also known as an unbounded wildcard. So you can specify any type of object in your generic.
For example the `List` class is declared as `List<?>`, because it can be a list of anything you want.
Resources:
- Effective java - Generics.pdf
- Java language specification - Type Arguments and Wildcards
- oracle.com - Java tutorials, wildcards
Problem
Possible Duplicate: What does List<?> mean in java generics? What does the question mark in Java generics' type parameter mean? Apologies but it was difficult trying to search for `<?>`. What does mean in regards to Java generics? I understand `<A extends B>` and `<A super B>`, but I have never seen this question mark on its own before.