This blog entry is for those who want to use Prolog queries from their Java program. I use swi-prolog, a free implementation of the Prolog language.<\/p>\n
The SWI-prolog installation includes the java jpl7 package (in the lib installation folder): To use it from java you need to setup some system variables before executing your app. Moreover, the java and swi-prolog installations must both be 32 bit or 64bit. For example you can edit a run.bat batch file with the following commands (assuming that swi-prolog is installed in c:\/program files\/swipl and your app is in the executable <your jar name>.jar file):<\/p>\n This approach assumes that the jpl.jar library file is included in your jar file, otherwise you must add the jpl.jar to the classpath variable. In the next blog entry<\/a> I explain how to do that using eclipse.<\/p>\n See an example that adds in the fact father(john,nikos)<\/em> to the prolog database and then runs the query father(X,nikos)<\/em>:<\/p>\n This blog entry is for those who want to use Prolog queries from their Java program. I use swi-prolog, a free implementation of the Prolog language. The SWI-prolog installation includes the java jpl7 package (in the lib installation folder): http:\/\/jpl7.org\/JavaApiOverview.jsp To use it from java you need to setup some system variables before executing your app. Moreover, … \u03a3\u03c5\u03bd\u03ad\u03c7\u03b5\u03b9\u03b1 \u03b1\u03bd\u03ac\u03b3\u03bd\u03c9\u03c3\u03b7\u03c2 Querying Prolog from Java<\/span>
\nhttp:\/\/jpl7.org\/JavaApiOverview.jsp<\/a><\/p>\n set SWI_PROLOG_PATH=c:\\program files\\swipl\n set path=%path%;%SWI_PROLOG_PATH%\\bin\\;%SWI_PROLOG_PATH%\\lib\\\n swipl.exe --dump-runtime-variables=cmd > plvars.bat\n call plvars.bat\n java -jar <your jar name>.jar<\/pre>\n
\nimport java.util.Map;\nimport org.jpl7.*;\n\npublic class TestPrologInterface {\n\n public static void main(String[] args) {\n String s = \"assert(father(john,nikos)).\";\n Query q = new Query(s);\n \/\/ run the query\n if (q.hasNext()) {\n \/\/ now I can ask for the father of nikos\n s = \"father(X,nikos).\";\n q = new Query(s);\n \/\/ run the query, repeat while there are more results\n while (q.hasNext()){\n \/\/get a mapping of variables to instantiations:\n\tMap<String, Term> map = q.next();\n\t\/\/get the instance of variable X\n\tString varX = map.get(\"X\").toString();\n\t\/\/print variable instance\n\tSystem.out.println(varX);\n }\n }\n }\n}\n<\/pre>\n","protected":false},"excerpt":{"rendered":"