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Wildcards in Java Generics - Tutorial

Wildcards in Java Generics - Tutorial  
 
 
ABSTRACT
 
 
Java Generics are the most ambitious extension added to the Java programming language since its advent in the mid '90ies. The basics of Java Generics, namely generic and parameterized types, are fairly easy to comprehend. Yet, the so-called wildcards, which can be used as type arguments of generic types and lead to constructs such as List<?> or Comparator<? super T> , are way more difficult to digest. Despite of the difficulties they pop up in many places in Java 5.0, most prominently in the java.util package. Even old fellows such as the getClass() method use wildcards these days. In essence, generics and wildcards cannot be ignored in Java 5.0. 

In this tutorial, we aim to explain wildcards in greater depth. What do they mean? How are they used? Are they of value in practice or are they an esoteric and acedemic exercise? Why do wildcard parameterized type behave that suprisingly? What else need I know to understand and use wildcards effectively? 

The tutorial is for Java developers who have studied the widely available generics tutorial and want to know more. The goal of this talk is not so much to explain the type theory, which is the foundation of generics and wildcards, but more to address practical issues in software development using Java generics or migrating to Java generics.

 
 
PREREQUISITES

 
 
Level: intermediate / advanced
Duration: 1.5 hours
Prerequisites: Attendants should be familiar with Java and have basic knowledge of Java generics.
Presented at: ACCU Conference , Oxford, UK, April 2005 
JAX 2005 , Frankfurt, Germany, May 2005 
 

If you are interested to hear more about this and related topics you might want to check out the following seminar or skim through some further reading:
Seminars
 
Effective Java
4 day seminar (open enrollment and on-site)
 
Papers
 
online FAQ Java Generics FAQ
Online FAQ
slides (pdf) Java Generics
JavaOne Presentation Slides
article Language Features of Java Generics
Article
  © Copyright 1995-2012 by Angelika Langer.  All Rights Reserved.    URL: < http://www.AngelikaLanger.com/Conferences/Abstracts/Wildcards.htm  last update: 4 Nov 2012