Java 5 Generics

[Srivatsan santhanam]

Hi,

I saw that in Java 5 we can make use of Generics to have declarations like

Set<String> s = new HashSet<String>();

but, Can i also use UserDefined Objects also ? like

Set<EmployeeName> s = new HastSet<EmployeeName>();

Does this Generics information also made part of the Genearated .class file (byteCode) ? or is it only meant for Java Compiler and is lost after compilation?


-Srivats

[Joni Salonen]

Yes, you can use user defined objects, as long as they fullfill the requirements of the container poses; e.g. HashSet requires you to implement the equals and hashCode methods or otherwise it won't work quite the way you might think.

The type information is lost when you compile. This is called "type erasure."
See also
http://java.sun.com/docs/books/tutorial/java/javaOO/generics.html
http://java.sun.com/developer/technicalArticles/J2SE/generics/index.html
http://java.sun.com/j2se/1.5/pdf/generics-tutorial.pdf