Very easy. Just add the rankingalgorithm.jar file to your classpath. Make sure lucene is also in the classpath, see examples below.
Add rankingalgorithm.jar and lucene.jar to your classpath. You can find them under dist and lib directories. See the example programs under examples, example.sh and simpleexample.sh on usage.
You can try out the RankingAlgorithm with example.sh and simpleexample.sh scripts. They use a sample lucene/index under examples. The sample index holds two documents with contents "ranking algorithm", "ranking hits".
Give it a try.
Step 1. unzip the downloaded rankingalgorithm.zip somewhere
Step 2. choose File->New->Java project
Step 3. click Create Project From Source
Browse and choose the directory where you unzipped zip rankingalgorithm.zip
Give the project a name
(this should import and try to compile the src/Example.java and src/SimpleExample.java. If you see errors, add dist/rankingalgorithm.jar and lib/lucene-core-2.9.3.jar to the classpath using project/properties/build path add jar option)
Step3. Click on Example java under src/examples in the new project
Step 4. Click Run Configurations and right mouse click to create a new run configuration
In the program arguments enter the below as args: path to an existing lucene index or [path to new project]/examples/lucene/index contents "ranking algorithm"
For eg: /project/examples/lucene/index contents "ranking algorithm"
Note: You can get the path to the index file by clicking on examples/lucene/index folder and then right mouse click to select properties, which should bring up a window with Location: showing the path
Step 5: Click apply and run the program