Category Archives: Java

Generating code with JavaPoet

Why write code when you can generate it? There are lots of situations when it makes more sense to generate. In this article I’m going to work through an example of how to use JavaPoet and Apache BeanUtils to write … Continue reading

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Writing a custom spliterator in Java 8

In this article I’m going to give two examples of writing a custom spliterator in Java 8. What is a spliterator and why would you need to write your own? Well, a spliterator is used by the Java streams code … Continue reading

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Using Optional in Java 8

“The introduction of null references was my billion dollar mistake” – Tony Hoare Optional is a (typed) container object. It may contain a single object, or it may be empty. It allows you to avoid null pointer exceptions. In this … Continue reading

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Java 8 Streams Tutorial

In this tutorial, I’m going to start by explaining some of the basics of streams. Viz: What streams are Terminal and non-terminal operations Their “lazy” nature Their read-once nature Why they were introduced i.e. how they enable easy parallel operations … Continue reading

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Yet another Java 8 custom collector example

Java 8 introduces a number of functional programming techniques to the language. Collections can be turned into streams which allows you to perform standard functional operations on them, such as filtering, mapping, reducing and collecting. In this post I’m going … Continue reading

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Hibernate example 4 – many to many associations

I’ve put some code on Github that shows three ways of modelling many to many associations with JPA / Hibernate: Using a join table that is not mapped as either an entity or an embedded component type. Mapping the join … Continue reading

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Hibernate example 3 – one to one associations

Just put a Hibernate example of the three different ways to create one-to-one associations on github: https://github.com/hedleyproctor/hibernate-one-to-one It contains a Customer entity, which has one-to-one associations to a UserProfile, MarketingPreferences and a Wistlist. Foreign key relationship. Customer has a foreign … Continue reading

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Hibernate example 2 – one-to-many associations

Just put an example of how to use one-to-many associations with Hibernate on Github: https://github.com/hedleyproctor/hibernate-one-to-many Shows two examples of a one-to-many relationship between entities: Unordered one-to-many between Customer and Address. Ordered one-to-many between Customer and PaymentCard. The unordered association uses … Continue reading

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Hibernate example 1 – inheritance and polymorphism

Have just put an example on Github of how to handle inheritance and polymorphism with Hibernate: https://github.com/hedleyproctor/hibernate-polymorphism It demonstrates the four ways of dealing with inheritance and polymorphism: Implicit polymorphism – no explicit mapping of the inheritance, but Hibernate can … Continue reading

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Testing Camel routes with Spring OSGi properties

If you are writing Camel routes using Spring to deploy to ServiceMix, you can’t use regular Spring properties, since ServiceMix is an OSGi container. Instead, you have to use OSGi properties. But if you try to start up your Spring … Continue reading

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