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Avoid Lazy JPA Collections

Hibernate (and actually JPA) has collection mappings: @OneToMany, @ManyToMany, @ElementCollection. All of these are by default lazy. This means the collections are specific implementations of the List or Set interface that hold a reference to the persistent session and the values are loaded from the database only if the collection is accessed. That saves unnecessary database queries if you only ...

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Scala Tutorial – objects, classes, inheritance, traits, Lists with multiple related types, apply

Preface This is part 9 of tutorials for first-time programmers getting into Scala. Other posts are on this blog, and you can get links to those and other resources on the links page of the Computational Linguistics course I’m creating these for. Additionally you can find this and other tutorial series on the JCG Java Tutorials page. This tutorial is about ...

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Play! Framework: Why Did I Fall in Love with it

Some time ago, I was the tech lead for a few very large deployments on the Real Estate market for companies like Fannie Mae, Freddie Mac, Foreclosure.com and HUD. We were running that traditional enterprise Java stack you are probably familiar with – Spring, Hibernate, Solr, etc. It took a few years but we had built a very nice system; ...

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Java EE6 CDI, Named Components and Qualifiers

One of the biggest promises java EE6 made, was to ease the use of dependency injection. They did, using CDI. CDI, which stands for Contexts and Dependency Injection for Java EE, offers a base set to apply dependency injection in your enterprise application. Before CDI, EJB 3 also introduced dependency injection, but this was a bit basic. You could inject ...

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Testing an Object’s Internal State with PowerMock

Most unit testing focuses on testing an object’s behaviour in order to prove that it works. This is achieved by writing a JUnit test that calls an object’s public methods and then testing that the return values from these calls match some previously defined set of expected values. This is a very common and successful technique; however, it shouldn’t be ...

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Top 10 Java Books you don’t want to miss

We learn by reading books and experimenting on it. So, it is imperative that you choose the best available options. In this post I would like to share my experience with some of the books and how they can help you evolve as a Java Developer. Lets start from the floor, the first 3 books are a good starting point ...

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Parametrizing custom validator in JSF 2

Writing a custom validator in JSF 2 is not a complicated task. You implement Validator interface, add @FacesValidator annotation and insert validator declaration in faces-config.xml, that’s all. A piece of cake. But let’s consider following scenario: You need custom date validator, let’s say checking that date from rich:calendar is not in the past. So we place calendar component with validator ...

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Vaadin add-ons and Maven

Introduction One (of the many) thing I like about Vaadin, is its community of ‘add-ons’ to the Vaadin framework – what they call the Vaadin Directory. An ‘add-on’ is a community-contributed addition to the framework, and can be anything from for example a new client-side widget to a Lazy loading container for a data table. Something similar I would definitely ...

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You can’t be Agile in Maintenance? (Part 2)

This article continues from You can’t be Agile in Maintenance? (Part 1) Coding Guidelines – follow the rules Getting the team to follow coding guidelines is important in maintenance to help ensure the consistency and integrity of the code base over time – and to help ensure software security (PPT). Of course teams may have to compromise on coding standards ...

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