Help Finishing a Java - Prolog Code

I want to write a code that uses A star algorithm for getting minimum distance. Imagine as an example you have 10 taxis and a client and you want to find the one that is closer. You calculate the minimum distance with A star algorithm. You show the results with kml. Most of the project is already done, we need the last smallest part. You get map data from openmaps (coordinates) which you use as nodes. Already Done: Full Java code for the first part full of comments. Parses all the data, calculates A star, writes them in KML. Considers that all roads are accessible and 2 way. Needs to be slightly changed. Connection with Prolog ready. All datasets fully accessible and easily manipulated. ToDo: Now we get some additional data (all datasets are ready). We have some restrictions to choose the right taxi, not only distance. Eg language of client taxi driver, number of passengers. So from java you call prolog and according to the answer we eliminate some taxis. Second part is that now some roads are one-way, so in A star you cannot choose to change direction however you want (so some nodes are not connected). Third part are that you calculate high traffic at some hours (from zero to 1), and according to that prolog alters the heuristic cost (A star fully ready and functional). Main functionality will be some prolog rules that say belongsTo(Χ, L) for nodes X that belong to road L, next(Χ, Υ) to what road crosses what road, canMoveFromTo(X, Y) :- ..., priority(R, T, Z) :- ... etc. Nodes (coordinates of each road) are stored in ArrayList so you need to know how to work with this library. Much more detailed info will be given, with exact tasks that needs to be done. With the initial Java code with prolog connection, with the prolog restrictions written in natural language.