There are quite often situations, when you’d need to add or substract a time period to a date when you are accessing the database via Java Persistence API(JPA). Now

  • the bad news is that Java Persistence Query Language(JPQL) does not support such operations on dates yet.
  • the good news is that it is possible by using a native query or doing the computation on the Java side. I prefer the second option as it provides database independence.
  • It was about “time”…

    Java SE 8 Date and Time

    by Ben Evans and Richard Warburton

    <head>
    <title>Hoisting example</title>
    </head>
    <body>
        <h1>Hoisting in action</h1>
        <script type="application/javascript">
            var hoisting = "global variable";
            alert("global 'hoisting' var => " + hoisting);
            (function(){
                alert("local 'hoisting' var (BEFORE declaration WILL NOT PICK its global 'shadow' -> undefined !) => " + hoisting);
                var hoisting = "local variable";
                alert("local 'hoisting' var (AFTER declaration WILL HIDE its global 'shadow' -> assigned value !) => " + hoisting);
                // block
                {
                    var hoisting = "block variable";
                    alert("block 'hoisting' var (AFTER declaration WILL OVERRIDE its local 'shadow' -> assigned value !) => " + hoisting);
                }
                // after block
                alert("local 'hoisting' var REPLACED AFTER BLOCK with its block 'shadow' => " + hoisting);
                // THE moral
                alert("The Hoisting MORAL: ALL local variables (even from blocks) are pre-defined/hoisted by JavaScript Runtime in front of the method body !\nDYI to make it clear !");
            })(); //self-executing function 
        </script>
    </body>

    Thank you Dev{eloper} Stonez (@devstonez) for the tip.

    1. References of used class/method in code

    This is a very quick and useful way to find out where a class or method is used throughout the workspace/project. How to do it – select class/method > right click > References > Workspace (Ctrl+Shift+G) || Project

    Once you’ve done that, the results will be displayed in the Search view:

    Show-References

    Show references

    Another alternative for that is by selecting the class/method > start Java Search (Ctrl+H) > select your search criteria (in this case Type) and limit to References:

    show references - java search

    Show References via Java Search

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    This is sort of a follow up post for a previous post of mine – RESTful Web Services Example in Java with Jersey, Spring and MyBatis. It is based on the same example application, which, via a REST API, can execute CRUD operations against a single Podcasts table. If in the first post the focus was on how to build the REST API with Jersey, this time it is on the data persistence layer. I will present how to implement a container-agnostic persistence layer with JPA2/Hibernate, being glued in the application via Spring.

    Continue Reading ...