Java on Lloyd Rochester's Geek Blog

User Name Search with Apache Lucene

Thu, 30 Jan 2020 10:53:31 +0000

User Name Search with Apache Lucene

I wanted to use Apache Lucene to search User Names. It’s definitely not straightforward. This post explains how to do it by defining our own custom Analyzer and explaining how we form the Document, index the user names and query with a PrefixQuery.

First of all if you’re using Apache Lucene you’re my type of person! It’s an awesome project, but the documentation and examples are severely lacking.

Java Cyclic Barrier

Mon, 25 Feb 2019 08:00:00 +0000

Java Cyclic Barrier

Imagine a scenario where you have N threads and can only do something when M of them are ready. Java already has this built in since 1.5 with the CyclicBarrier.

From the Javadoc we see the CyclicBarrier is A synchronization aid that allows a set of threads to all wait for each other to reach a common barrier point. CyclicBarriers are useful in programs involving a fixed sized party of threads that must occasionally wait for each other. The barrier is called cyclic because it can be re-used after the waiting threads are released.

Java Multicore Example

Sun, 24 Feb 2019 14:57:00 +0000

Java Multicore Example

Any program these days that does any significant computational load should utilize the available processor cores. In this post we’ll show an example using Java where we schedule Callables on all available processor cores. In Java a Callable is task that returns a result and may throw an exception. It is very similar to a Thread, but gives a much easier way to return the result asynchronous computation. I typically don’t see many reasons to not use Callables over Threads, since even if you don’t want or need to return the result you can still return some sort of status code. This blurb is directly from the Javadoc The Callable interface is similar to Runnable, in that both are designed for classes whose instances are potentially executed by another thread. A Runnable, however, does not return a result and cannot throw a checked exception.