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Bird’s Eye View on ElasticSearch its Query DSL
I’ve copied the whole post into a gist so that you can simply clone, copy and paste the important stuff and even could contribute easily. Several times per month there pop up questions regarding the...
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Assignment Algorithms to improve Perfomance of Automated Timetabling
Update: Was reblogged at dzone.com Last two days I’ve read the old Java code of a board game. Although the game still compiles and works (it even works on a Zaurus device) the code itself is horrible:...
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Rage Against the Android – Nearly solved! #eclipse #netbeans
After ranting against Android in my previous post I have mainly solved now the untestable situation Android is producing. Thanks to Robolectric all my tests are finally fast and do not unpredictable...
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Free Online Graph Theory Books and Resources
A link compilation of some Hackernews and Stackoverflow posts and a longish personal investigation. The DaMN book and its companion book Graph Theory with Applications, J.A. Bondy and U.S.R. Murty...
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Memory Efficient Java – Mission Impossible?
First, the normal usage in Java leads to massive memory waste as its pointed out in several articles or here in a nice IBM article. Some examples for the 32 bit JVM: Using 3 * 4 bytes for an object...
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Spatial Keys – Memory Efficient Geohashes
When you are operating on geographical data you’ll use latitude and longitude to specify a location somewhere on earth. To look up some associated information or if you want to do neighborhood searches...
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Tricks to Speed up Neighbor Searches of Quadtrees. #geo #spatial #java
In Java land there are at least two quadtree implementations which are not yet optimal, so I though I’ll post some possibilities to tune them. Some of those possibilities are already implemented in my...
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Failed Experiment: Memory Efficient Spatial Hashtable
The Background of my Idea The idea is to use a hash table for points (aka HashMap in Java) and try to implement neighbor searches. First of all you’ll need to understand what a spatial key is. Here you...
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Running Shortest-Path Algorithms on the German Road Network within a 1.5GB JVM
Update: With changes introduced in January 2013 you only need 1GB – live demo! In one of my last blog posts I wrote about memory efficient ways of coding Java. My conclusion was not a bright one for...
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Make Your Dijkstra Faster
Today I stumbled over yet another minor trick which could speed up the execution of the Dijkstra algorithm. Let me shortly introduce this shortest path algorithm: If you need the path (and not only the...
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Preparing GraphHopper for its first release … (#Java #OpenStreetMap #Graph)
I’ve not blogged since a while but we are pushing Java road routing via GraphHopper to its first public release 0.1! We’re not finished yet, but have a first look and give us feedback here or in the...
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GraphHopper Maps – High Performance and Customizable Routing in Java
Today we’re proud to announce the first stable release of GraphHopper! After over a year of busy development we finally reached version 0.1! GraphHopper is a fast and Open Source road routing engine...
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Java on iPhone or iPad
What options do I have to make my Java application working on the iPhone? It should not be necessary to jailbreak the phone. Also UI is not necessary for now although e.g. codenameone seems to support...
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Setup Mapnik From Scratch
THIS document is a work in progress. There are several options but mainly three web map servers (WMS): Mapnik, GeoServer and MapServer. Simple visualization: A) browser/client (leaflet, openlayers) |...
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Free the Java Duke now and use it in Blender!
Duke, the Java mascot is a well known ambassador for Java. It is so important even Oracle still has a prominent site for it. The only problem is that the original source files can only be opened with a...
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Releasing GraphHopper 0.2 – Further & Faster Road Routing!
Today we’re releasing version 0.2 of our Open Source road routing engine GraphHopper written in 100% Java. Faster! All algorithms are faster due to bug fixes and fine tuning A preparation is necessary...
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GraphHopper an Open Source and Cost Efficient Alternative to Google Maps API
On Monday we released version 0.2 of GraphHopper an Open Source road routing engine. GraphHopper is comparable fast to Google or Bing Maps, but if you use it in a LAN or directly from within your...
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GraphHopper News: Article in Java Magazine and FOSDEM 2014
Today the new Java Magazine from Oracle was published. You’ll need to register to view it or download one of the apps (Android, iOS). In this latest magazine my article about GraphHopper was published....
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GraphHopper in the Browser: TeaVM makes Offline Route Planning possible in...
Today I can make an exciting news. Alexey Andreev is the author of a Java-bytecode to Javascript compiler called TeaVM. You may know GWT or Scala.js but TeaVM does not compile the sources, it compiles...
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Releasing GraphHopper 0.3 – Plan Your Outdoor Trips Beyond Two Dimensions
Today we are happy to finally release version 0.3 of GraphHopper – the Open Source road routing engine. Here is a screenshot showing our slightly polished UI It shows a route result where elevation was...
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