In this java program, we are going to learn how to validate user input?
Here, we are reading an integer value, if someone’s input is not an integer it will through an error and reads the value again.
So, if you’re interested in learning how to do all these things without having to climb a steep learning curve, you can check these shorter posts to learn how to validate individual properties and fields and how to use Alejandro Gervasio is a senior System Analyst from Argentina who has been involved in software development since the mid-80's.
He has more than 12 years of experience in PHP development, 10 years in Java Programming, Object-Oriented Design, and most of the client-side technologies available out there.
Considering that in this case the array contains only an empty string, the precondition of method is just as simple as passing to it the constructor of the target class along with the corresponding arguments.
In this case, I deliberately passed in an array of empty strings, which causes the method to trigger two constraint violations.
We could put this functionality to work for us and use an interceptor for encapsulating validation logic in one place and intercepting calls to constrained methods in target objects, in order to validate the corresponding constraints.
In a nutshell, we’ll be implementing the long-awaited automatic method validation!
In addition, we saw that it’s possible to integrate the standard with CDI and Java EE interceptors and trigger automatic method validation.Look at the following domain class: annotation, followed by the interceptor class, enclosed in parenthesis.The annotation links the constrained methods to the interceptor, which means that whenever the methods are invoked, the calls can be intercepted and the constraints can be validated by following a specific strategy.Here’s how a typical method interceptor might be implemented: will result in two constraint violations being printed to the console, due to the transparent action of the interceptor.If you feel in the proper mood and want to implement your own interceptors or even tweak the one shown above, first off make sure to give a read to the official docs.The validations explained there use the It’s really easy to track down the contract agreed by the target class with the caller without having to scan the class from top to bottom and take a deeper look at method implementations.