marker interface

[Chan Apex]

I have confusion in using marker interface..what's the functionality of marker interface..

[Mohamed Sanaulla]

Apex han wrote:I have confusion in using marker interface..what's the functionality of marker interface..

They are interfaces with no methods. They tell the compiler to treat the classes implementing them differently. They usually used to categorize the classes based on their purpose. Good examples of these are: Serializable , Clonable.

Found an useful link: Are Marker Interfaces Dead?

[Ernest Friedman-Hill]

mohamed sanaullah wrote:They tell the compiler to treat the classes implementing them differently.

No. They do not tell the compiler anything. They are not magical in any way. For every use of a marker interface -- Serializable, Cloneable, or any other -- there is plain old Java code somewhere doing something like

if (theObject instanceof Serializable) {
   ...

That is all. Compilers know nothing about them. The JVM itself knows nothing about them.

Found an useful link: Are Marker Interfaces Dead?

Although some of what this article says is true, it contains the mistakes made in the post above, so far from considering it useful, I'd consider it harmful.

[Mohamed Sanaulla]

Thanks a lot for clearing the doubt. I knew that they are empty interfaces and had a fair idea about it. But yeah its foolish of me to actually believe most of the article. Considering it was on DZone- I thought it would have relevant information.