How should I write my own custom Annotation in Java

Question

Let say I want to check condition[let say boundary values] on some of the method arguments.Instead of writing "if" condition to check [boundary condition] on every method, I want to annotate argument only. Let me know the Steps to understand it. Working code will be awesome.

Answer 1

You need to look into method interception. What you are wanting is an interceptor that can validate method arguments on invocation. I like the AOP Alliance interfaces for this, they work pretty well. It also integrates with Guice natively and I think Spring has support for it as well.

Steps:

1. Define an annotation
2. Create an interceptor to process the annotation
3. Bind the interceptor (manually or using some framework)