Hi all, I am currently looking at Drools planner. I try to solve a simple 4 queens problem with the following code: XmlSolverConfigurer configurer = new XmlSolverConfigurer(); configurer.configure("/org/drools/planner/myexamples/nqueens/app/nqueensSolverConfig.xml"); Solver solver = configurer.buildSolver(); NQueensGenerator generator=new NQueensGenerator(); Solution startingSolution = generator.createNQueens(4); solver.setStartingSolution(startingSolution); solver.solve(); Solution bestSolution = solver.getBestSolution(); System.out.println((NQueens) bestSolution); The config file is the usual one: <?xml version="1.0" encoding="UTF-8"?> <localSearchSolver> <environmentMode>DEBUG</environmentMode> <scoreDrl>/org/drools/planner/examples/nqueens/solver/nQueensScoreRules.drl</scoreDrl> <scoreDefinition> <scoreDefinitionType>SIMPLE</scoreDefinitionType> </scoreDefinition> <!-- Real world problems require to use of <startingSolutionInitializerClass>. --> <termination> <terminationCompositionStyle>OR</terminationCompositionStyle> <maximumStepCount>100</maximumStepCount> <scoreAttained>0</scoreAttained> </termination> <selector> <moveFactoryClass>org.drools.planner.examples.nqueens.solver.move.factory.NQueensMoveFactory</moveFactoryClass> </selector> <acceptor> <completeSolutionTabuSize>1000</completeSolutionTabuSize> </acceptor> <forager> <pickEarlyType>NEVER</pickEarlyType> <!-- Real world problems require to use of <minimalAcceptedSelection> --> </forager> </localSearchSolver> I do not understand why but it does not work: 2010-11-17 11:15:13,791 [main] INFO Solving with random seed (0). 2010-11-17 11:15:13,793 [main] INFO Initialization time spend (4) for score (0). Updating best solution and best score. Exception in thread "main" java.lang.ClassCastException: org.drools.planner.myexamples.nqueens.domain.NQueens at org.drools.planner.examples.nqueens.solver.move.factory.NQueensMoveFactory.createCachedMoveList(NQueensMoveFactory.java:35) at org.drools.planner.core.move.factory.CachedMoveFactory.solvingStarted(CachedMoveFactory.java:39) at org.drools.planner.core.localsearch.decider.selector.MoveFactorySelector.solvingStarted(MoveFactorySelector.java:58) at org.drools.planner.core.localsearch.decider.DefaultDecider.solvingStarted(DefaultDecider.java:91) at org.drools.planner.core.localsearch.DefaultLocalSearchSolver.solvingStarted(DefaultLocalSearchSolver.java:188) at org.drools.planner.core.localsearch.DefaultLocalSearchSolver.solveImplementation(DefaultLocalSearchSolver.java:125) at org.drools.planner.core.AbstractSolver.solve(AbstractSolver.java:57) at org.drools.planner.myexamples.nqueens.app.Main.main(Main.java:32) Any idea ? Thanks in advance, MM. -- View this message in context: http://drools-java-rules-engine.46999.n3.nabble.com/Simple-Drools-Planner... Sent from the Drools - User mailing list archive at Nabble.com.