At the release of Java 8 the most attention went to the Lamda’s, the new Date API and the Nashorn Javascript engine. In the shade of these, there are smaller but also interesting changes. Amongst them is the introduction of a StringJoiner. The StringJoiner is a utility to delimit a list of characters or strings. You may recognize the code below:

String getString(List<String> items)
    StringBuilder sb = new StringBuilder();
    for(String item : items) {
        if(sb.length != 0) {
            sb.append(",");
        }
        sb.append(item);
    }
    return sb.toString();
}

Continue reading →

When we want to clone an object there are several ways to do this For instance we can implement Clonable, which makes it possible to duplicate an object. We also can create a new object manually by calling each setter or use a parameterised constructor. In case we want to clone a Hibernate object, there is an extra option available which is more elegant: the Hibernate3BeanReplicator. The Hibernate3BeanReplicator is provided by Beanlib (http://beanlib.sourceforge.net/) and it supports deep clones, so we can also clone related one-to-one objects easily. For example we want to clone the Student object, including all child (one-to-one) objects.

Student student = studentDao.getStudentById(1);

HibernateBeanReplicator replicator = new Hibernate3BeanReplicator();
Student studentCopy = replicator.deepCopy(student);

studentCopy.setId(null);
studentCopy.getRelatedObject().setId(null);

studentDao.save(studentCopy);

Continue reading →

Apache Wicket is a populair web framework. There are a many reasons why I like to use Wicket, for instance: it offers a great mark-up/logic separation and using Wicket it’s very easy to implement AJAX functionality without writing one line of Javascript.

To provide you with simple and short tips and tricks for Wicket I write this series of blogs. In this first blog of the series I will show you how to create a download link in several ways.

Continue reading →

While writing unit tests, you often have to mock dependencies like services or controllers. Often  a constructor is used to autowire the dependencies as shown in the example below. In the Test class I instantiated the ContactService using a contactRepository Mock object

@Service
public class ContactServiceImpl implements ContactService {

private final ContactRepository contactRepository;

    @Autowired
    public ContactServiceImpl(final ContactRepository contactRepository) {
    this.contactRepository = contactRepository;
    }

    public void saveContact(final Contact contact) {
    contactRepository.save(contact);
    }
}

Continue reading →

Spring made it very easy to consume JSON webservices. In this article I describe how to receive and parse JSON and how to send your Java objects as JSON. First we need to include the required dependencies. If you use maven, include the following dependencies:

<dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-web</artifactId>
      <version>3.1.2.RELEASE</version>
</dependency>
<dependency>
      <groupId>org.codehaus.jackson</groupId>
      <artifactId>jackson-mapper-asl</artifactId>
      <version>1.9.9</version>
</dependency>

Continue reading →