Java collection framework is not that powerful as experienced Java developer would expect. For example, how do you sort a list? Simple answer would be to use java.util.Collections.sort() method with some kind of java.util.Comparator implementation. Additionally Guava Ordering support can be used. However, the solution is not exactly what object oriented developer looks for. Similarly to … Read more
Inspired by a few talks during the last 33rd Degree conference I decided to implement, in one of the applications I develop, metrics which allow developers or operation team monitor running application and possibly detect potential problems early on. After a quick investigation I decided to use the Metrics framework. What I expected was exposing at least some statistics … Read more
Some time ago I signed up for a beta testing of a new tool from Zeroturnaround : Xrebel. I have been waiting a bit impatiently for a testing program to start. Finally I have got an information about availability of 1.0.0 version of the tool for download. Without much hesitation I have started tests. What … Read more
Recently, I have come across a nasty bug. When Hibernate executes a cacheable query and applying a ResultTransformer on a result of that query, java.lang.ClassCastException is thrown. session.createCriteria(RateEntity.class) .add(Restrictions.eq(CURR_ID, criteria.getCurrency())) .add(Restrictions.eq(TYPE, criteria.getRateType().name())) .add(Restrictions.gt(TS_CRT, criteria.getFromTime().toDate())) .setProjection(Projections.projectionList() .add(Projections.property(TS_CRT), TIME_DTO_PROPERTY) .add(Projections.property(RATE), RATE_DTO_PROPERTY)) .addOrder(Order.asc(TS_CRT)) .setCacheable(true) .setResultTransformer(Transformers.aliasToBean(RateDTO.class)) .list(); It seems that the ResultTransformer is applied on the result before putting … Read more
Let’s consider the following code snippets: public enum Currency { EUR, USD } String currency = “EUR”; if(Currency.EUR.name().equals(currency)){ System.out.println(“Transfer permitted”); } How often do we see much the same scenario? It is not completely wrong since there is a try to use enums so it is not entirely “string driven” programming. However there is … Read more
I am going to present quick overview of useful tools which can be helpful when you trying to troubleshoot application in case of performance issues. Describing each tool, some overview is provided, the way the tool is installed, free/paid info, inclusion in the JDK and the information if it can be used in production environment. … Read more
I have run into interesting issue recently. I use in the project JPA + Hibernate + EJB. The issue concerns saving and deleting entities in the same transaction. Database table which is used has an unique constraint defined on two columns. What I have done was removing entity calling entityManager.remove(); then the new entity has … Read more
I have been really impressed by the Spring Integration project recently so I decided to write a few words about it. Just to make a quick introduction: Spring Integration can be described as an extension of the Spring programming model which supports Enterprise Integration Patterns. It enables lightweight messaging within Spring-based applications and supports integration … Read more