CODEWITHSUNDEEP
javaservletsjboss
Ashwin
Ashwin

Reputation: 13547

Create a class that is accessible to the whole application

In android there is a mechanism of ensuring that only one instance of a class is available to the whole application. This can be done by deriving that class from Application.

Can some thing similar be done in servlets? I want to initialize a class when the application is deployed. This class should have only one instance. So that what all the servlets can access it.
I came to know that you can store your data in the servlet context's hashmap. But I don't want to do that. I want to write my own class with its functions. How should this be done?

Upvotes: 0

Views: 375

Answers (3)

aioobe
aioobe

Reputation: 421130

I think what you're after is simply a singleton.

This is best implemented by defining an enum with a single instance. (Note that enums allow you to have member functions just as classes.)

public enum YourSingleton {

    INSTANCE;

    // Your methods...

}

and then you access it as

YourSingleton.INSTANCE

Upvotes: 4

RP-
RP-

Reputation: 5837

Use singleton pattern so the first call to instance method (say YourClass.getInstance()) will create the instance and it will be reused across the application.

Upvotes: 1

Sean Owen
Sean Owen

Reputation: 66896

So, create whatever class you want with its own functions or whatever you like, and put that in the ServletContext at startup. You can use a ServletContextListener to initialize and remove it. What's limiting about that?

Upvotes: 4

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