Instance Variable In Servlet

[javarishi]

Can we have instance and static variable in Servlet.

[Nicholas Jordan]

Yes. The code is exactly the same as always. Try it, see what you get.

[javarishi]

It Compiles. But In Running Environment Is There Any Problem?

[masijade]

Web Application Servers are threaded and normally operate as follows:

1. The Web Container instantiates the servlet as soon as the application context is started (or, by some, as soon as the first request for it comes in).

2. A request arrives for that servlet.

3. The Web Container starts a thread with this already instantiated Servlet.

As you can see from above, there is only one instance of this Servlet, regardless of the number of concurrent requests for it, so, the varying users using (and definately even worse changing) information in these instance variables will stepping all over each other, as they will all be using the same instance of the Servlet.