One of the most profound insights I have learnt about OO is that software design — the shaping of code & classes — is best informed by what processing needs to do, rather than the entities it goes between.
This makes sense on a fundamental level. The purpose of most software is to process & transform data. Algorithms (like quicksort for example) have the same structure, regardless of what data they’re processing. In short, design of the machine should be based on what does it do rather than what its inputs look like at rest. Continue reading
Real software sees entities (Customer, File etc) involved in multiple interactions. Simple OO examples model behavior in entity classes directly, but this becomes tangled as behaviors & interactions increase; and results in broken inheritance structures.
Instead of modelling these all in the entity, a more advanced OO approach considers separating behavior from the entity. We’ll consider key principles in this multi-part series. Continue reading
HttpClient has long been popular for implementing outbound HTTP in Java. URL requests, HTTP remoting & service access are all common usecases.
For developers of HTTPS client applications, one scenario is common: wanting to test HTTPS connectivity, without needing a CA-signed certificate on each developer’s local appserver. Continue reading
Oracle 12c’s new feature is pluggable databases (PDBs). This has been introduced to improve support for cloud & multi-tenancy, and keep up with SQL Server. However, our trial found Oracle’s PDBs less than ready for production use. Continue reading
Exception handling in Java is crucial for reliability, but a common source of bloat & prone to miscoding. However, dealing with exceptions correctly can be surprisingly easy.
We cover 10 “foundation” best practices to simplify your coding & help you handle exceptions correctly. Continue reading
Oracle, with lead engineer Brian Goetz, have launched an experimental OpenJDK project to bring long-awaited features to the Java platform.
Major enhancements to generics & new ‘value types’ are planned. Highlights include:
- Value Types; highly-efficient small ‘objects’ without inheritance.
- Reified Generics; retaining their actual type at runtime.
- Generic Specialization; List<int> would be valid & highly efficient.
- ‘volatile’ enhancements.
The effort is named Project Valhalla. Here’s a preview: Continue reading
With the move to annotations for use of Spring, many projects have become based on component-scanning, auto-wiring and property-placeholder injection — an ‘implicit’ approach to configuration.
However, it can still be very useful to specify ‘explicit’ configuration. This gives us control of top-level application config & enables extensible configuration using the Strategy pattern.
Gaining control of configuration is crucial to enable per-customer/ per-application customization. Continue reading
Java 8′s ForkJoinPool & parallel streams are receiving some serious attention now. They seem a sophisticated concept to parallelize work, but some are warning of serious limitations.
Edward Harned of CoopSoft, in particular, has analyzed the Fork/Join design implemented in Java. Continue reading
Checked exceptions have always been a controversial feature of the Java language.
Advocates claim they ensure checking & recovery from failures. Detractors say “catch” blocks can almost never recover from an exception, and are a frequent source of mistakes.
Meanwhile, Java 8 and lambdas are here. Are checked exceptions becoming obsolete in the Java world? Continue reading
Threading is easy in Java, but today I was reminded of another of its pitfalls.
In Java- or container-provided threads, unhandled exceptions from our code will be printed or logged to the console. Create your own
Thread or use
ThreadPoolExecutor, and it’s a different story..
Threaded code tends to die silently. Nothing on the console or logs. Unhandled exceptions are invisible, and leave very few clues. Let’s look at why.