Generics in java

[ajeeb]

Hi,
I recently started looking into generics (a feature from java 5 onwards). Everything was fine until I somehow came across the Enumeration interface source code:

package java.util;

public interface Enumeration<E> {

boolean hasMoreElements();

E nextElement();
}

What is the 'E' over here ? Any ideas ?

[toadaly]

'E' represents the generic type.

[fishtoprecords]

What is the 'E' over here ? Any ideas ?

Its a dummy variable for the type, in other classes its a T or K or V.

Enumeration<String> e = ...

is how you get type safety of a String.

Sun has some very nice tutorials on this stuff, you should take a quick read.

[ajeeb]

I got the idea. Its indeed a dummy variable stating that the Enumeration will contain objects of type E. Thanks to all.

[masijade]

P.S. The developers chose the letter (normally) depending on what they wanted to "say". E normally stands for Element, T Type, K Key, and V Value. Not that that really makes any difference. ;-)

[Steve11235]

Just a note: The generic type names don't have to be a single, uppercase letter. They can just as easily be Element, Key, Value, AnythingElseThatMakesSense. When I started using them in my own classes, I didn't know what letters I could use...