Generics in the Java Programming Language

Source: java.sun.com
Topic: Java Programming

Short Desciption:
JDK 1.5 introduces several extensions to the Java programming language. One of these. is the introduction of generics. This tutorial is aimed at introducing ...

 

Content Inside:
Generics in the Java Programming LanguagePage 1Generics in the Java Programming LanguageGilad BrachaJuly 5 2004Contents1 Introduction22 Defining Simple Generics33 Generics and Subtyping44 Wildcards54.1 Bounded Wildcards . . . . . . . . . . . . . . . . . . . . . . . . . . .65 Generic Methods76 Interoperating with Legacy Code106.1 Using Legacy Code in Generic Code . . . . . . . . . . . . . . . . . .106.2 Erasure and Translation . . . . . . . . . . . . . . . . . . . . . . . . .126.3 Using Generic Code in Legacy Code . . . . . . . . . . . . . . . . . .137 The Fine Print147.1 A Generic Class is Shared by all its Invocations . . . . . . . . . . . .147.2 Casts and InstanceOf . . . . . . . . . . . . . . . . . . . . . . . . . .147.3 Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .158 Class Literals as Runtime Type Tokens169 More Fun with Wildcards189.1 Wildcard Capture . . . . . . . . . . . . . . . . . . . . . . . . . . . .2010 Converting Legacy Code to Use Generics2011 Acknowledgements231Page 21 IntroductionJDK 1.5 introduces several extensions to the Java programming language. One of theseis the introduction of generics.This tutorial is aimed at introducing you to generics. You may be familiar withsimilar constructs from other languages most notably C++ templates. If so youll soonsee that there are both similarities and important differences. If you are not familiarwith lookaalike constructs from elsewhere all the better; you can start afresh withoutunlearning any misconceptions.Generics allow you to abstract over types. The most common examples are container types such as those in the Collection hierarchy.Here is a typical usage of that sort:List myIntList = new LinkedList(); // 1myIntList.add(new Integer(0)); // 2Integer x = (Integer) myIntList.iterator().next(); // 3The cast on line 3 is slightly annoying. Typically the programmer knows whatkind of data has been placed into a particular list. However the cast is essential. Thecompiler can only ...

 

 

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