in Java syntax, Class<? extends Something>

Question

Class<? extends Something>

Here's my interpretation, it's class template but the class ? means the name of the class is undetermined and it extends the Something class.

if there's something wrong with my interpretation, let me know.

Answer 1

There are a few confusing answers here so I will try and clear this up. You define a generic as such:

public class Foo<T> {     private T t;     public void setValue(T t) {         this.t = t;     }     public T getValue() {         return t;     } } 

If you want a generic on Foo to always extend a class Bar you would declare it as such:

public class Foo<T extends Bar> {     private T t;     public void setValue(T t) {         this.t = t;     }     public T getValue() {         return t;     } } 

The ? is used when you declare a variable.

Foo<? extends Bar>foo = getFoo(); 

OR

DoSomething(List<? extends Bar> listOfBarObjects) {     //internals }