Intégration. OCR. Template generator - Heroku Java. James Ward | Heroku | Java | Scala | Cloud | Open Source | Linux. Regular expressions. Java. Java/JEE. Ruby & Java. Java Bien! Optimize a query on a Map - Java World. In "Optimizing a query on a collection", I considered how to optimize a query on an indexable collection. However, optimizing queries on Map classes turns out to be more complicated. In this article, I'll provide an example of how you can speed up bottlenecks consisting of Map queries. The query First I'll start with the problem. I'll use strings as keys for my collection.
For their corresponding values, I'll simply use integer objects to indicate some value object. Key -> value"code" -> 1"rode" -> 2"load" -> 3"toad" -> 4"road" -> 5 The query in that case might be "sum of the values for those string keys in the map that contain the substrings od or lo" (the answer would be 1+2+3=6 for this example list). For my actual keys, I'll generate multicharacter strings by using lowercase letters (a to z). I've chosen to use an easily generated collection for the data and a straightforward query to avoid any application-specific distractions. The simple straightforward version of the query is: with: Get size of object in memory. Occasionally, you may be interested in measuring (or estimating) the size of an object in memory.
Here's a utility which can help with that task, if the object's class has a no-argument constructor. It follows the style used by Java Platform Performance, by Wilson and Kesselman. Given a class name, it will build a number of objects using the no-argument constructor, and measure the effect on JVM memory use. Thus, it measures the size of 'empty' objects containing no data. To measure the size of a particular object containing data, a similar technique can easily be used: measure JVM memory use before and after building the object.
ObjectSizer can be easily placed in an interactive console application. An example run gives: >java -cp . Bye. Here is the Interpreter class: Eclipse - JDK 8 - "The type java.util.Map$Entry cannot be resolved" April 1, 2014 | Play Framework with Java 8 | Typesafe. In case you missed our recent post Go Reactive with Java 8 or the follow-up webinar, a stable release of Java 8 is now available and is supported by the Play Framework. Some of the new Java features lend themselves well to developing Reactive applications with Play, and I’ll show you how to use them. If you’re new to Play, it’s a modern web application framework that is designed to meet the tenets of Reactive Programming. Play gives you the foundation to make scalable and responsive applications based on Functional Programming patterns. This is natural to do in Play and using Java 8 makes these patterns clearer and more concise. I’m going to demonstrate how to do this using sample code taken from the Typesafe Activator template “Go Reactive with Java 8 & Play.”
I’ll start by showing a synchronous (blocking) controller action: This action uses the same thread to handle a request, execute longRunningCalculation(), construct a Result, and serve a response.