爲什麼optaplanner在調用move.doMove（guiScoreDirector）時爲空指針;

Question

我的optaplanner web應用程序出現問題。這個應用程序是基於車輛演示網​​站示例。我想在課程時間表的Web示例中實現一個手動doChangeMove函數。我的代碼（courseTimeTablingManager.java）情況如下：

public synchronized boolean solve(final String sessionId) { 

    //final Solver<CourseSchedule> solver = solverFactory.buildSolver(); 

    Solver<CourseSchedule> solver; 
    if(sessionSolverMap.containsKey(sessionId)){ 
     solver = sessionSolverMap.get(sessionId); 
    }else{ 
     solver = solverFactory.buildSolver(); 
    } 
    //solver = solverFactory.buildSolver(); 
    solver.addEventListener(new SolverEventListener<CourseSchedule>() { 
     @Override 
     public void bestSolutionChanged(BestSolutionChangedEvent<CourseSchedule> event) { 
      CourseSchedule bestSolution = event.getNewBestSolution(); 
      synchronized (CourseTimeTablingManager.this) { 
       sessionSolutionMap.put(sessionId, bestSolution); 
      } 
     } 
    }); 
    if (sessionSolverMap.containsKey(sessionId)) { 
     return false; 
    } 
    sessionSolverMap.put(sessionId, solver); 
    final CourseSchedule solution = retrieveOrCreateSolution(sessionId, xml); 
    executor.submit(new Runnable() { 
     @Override 
     public void run() { 
      Solver<CourseSchedule> solver = sessionSolverMap.get(sessionId); 
      CourseSchedule bestSolution = solver.solve(solution); 
      synchronized (CourseTimeTablingManager.this) { 
       sessionSolutionMap.put(sessionId, bestSolution); 
       //sessionSolverMap.remove(sessionId); 
      } 
     } 
    }); 
    return true; 
} 

public synchronized boolean terminateEarly(String sessionId) { 
    //Solver<CourseSchedule> solver = sessionSolverMap.remove(sessionId); 
    Solver<CourseSchedule> solver = sessionSolverMap.get(sessionId); 
    if (solver != null) { 
     solver.terminateEarly(); 
     return true; 
    } else { 
     return false; 
    } 
} 

public synchronized ChangeMove createChangeMove(Object entity, String variableName, Object toPlanningValue, String sessionId) { 
    // TODO Solver should support building a ChangeMove 
    Solver<CourseSchedule> solver = sessionSolverMap.get(sessionId); 
    ScoreDirectorFactory scoreDirectorFactory = solver.getScoreDirectorFactory(); 
    guiScoreDirector = scoreDirectorFactory.buildScoreDirector(); 
    InnerScoreDirector guiInnerScoreDirector = (InnerScoreDirector) this.guiScoreDirector; 
    SolutionDescriptor solutionDescriptor = guiInnerScoreDirector.getSolutionDescriptor(); 
    GenuineVariableDescriptor variableDescriptor = solutionDescriptor.findGenuineVariableDescriptorOrFail(
      entity, variableName); 
    if (variableDescriptor.isChained()) { 
     SupplyManager supplyManager = guiInnerScoreDirector.getSupplyManager(); 
     SingletonInverseVariableSupply inverseVariableSupply = supplyManager.demand(
       new SingletonInverseVariableDemand(variableDescriptor)); 
     return new ChainedChangeMove(entity, variableDescriptor, inverseVariableSupply, toPlanningValue); 
    } else { 
     return new ChangeMove(entity, variableDescriptor, toPlanningValue); 
    } 
} 

public synchronized void doChangeMove(Object entity, String variableName, Object toPlanningValue, String sessionId) { 
    ChangeMove move = createChangeMove(entity, variableName, toPlanningValue, sessionId); 
    doMove(move, sessionId); 
} 

public synchronized void doMove(Move move, String sessionId) { 
    Solver<CourseSchedule> solver = sessionSolverMap.get(sessionId); 
    if (solver.isSolving()) { 
     //logger.error("Not doing user move ({}) because the solver is solving.", move); 
     System.out.println("!!!!!!!!!!!!!!!!!! Not doing user move ({}) because the solver is solving."); 
     return; 
    } 
    if (!move.isMoveDoable(guiScoreDirector)) { 
     System.out.println("################## Not doing user move ({}) because it is not doable.");    
     return; 
    } 
    //System.out.println("------------------ doing user move ({}) .");   
    move.doMove(guiScoreDirector); // <----- Here, crash with NULL pointer!! 
    System.out.println("------------------ doing user move done ({}), try update score ... .");  
    guiScoreDirector.calculateScore(); 
} 

每次我運行的應用程序，它會在功能doMove的move.doMove（guiScoreDirector）崩潰。唯一的例外是：

Caused by: java.lang.NullPointerException 
at org.optaplanner.core.impl.score.director.drools.DroolsScoreDirector.update(DroolsScoreDirector.java:157) 
at org.optaplanner.core.impl.score.director.drools.DroolsScoreDirector.afterVariableChanged(DroolsScoreDirector.java:152) 
at org.optaplanner.core.impl.heuristic.selector.move.generic.ChangeMove.doMoveOnGenuineVariables(ChangeMove.java:69) 
at org.optaplanner.core.impl.heuristic.move.AbstractMove.doMove(AbstractMove.java:34) 
at org.optaplanner.webexamples.tt.rest.cdi.CourseTimeTablingManager.doMove(CourseTimeTablingManager.java:232) 
at org.optaplanner.webexamples.tt.rest.cdi.CourseTimeTablingManager.doChangeMove(CourseTimeTablingManager.java:217) 
at org.optaplanner.webexamples.tt.rest.cdi.CourseTimeTablingManager$Proxy$_$$_WeldClientProxy.doChangeMove(Unknown Source) 
at org.optaplanner.webexamples.tt.rest.service.DefaultCourseTimeTablingRestService.move(DefaultCourseTimeTablingRestService.java:179) 
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) 
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
at java.lang.reflect.Method.invoke(Method.java:498) 
at org.jboss.resteasy.core.MethodInjectorImpl.invoke(MethodInjectorImpl.java:137) 
at org.jboss.resteasy.core.ResourceMethodInvoker.invokeOnTarget(ResourceMethodInvoker.java:296) 
at org.jboss.resteasy.core.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:250) 
at org.jboss.resteasy.core.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:237) 
at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:356) 
... 32 more 

誰能幫助？提前致謝！

Answer 1

我假設實體（演講？）爲空。通過爲NullPointerException添加調試斷點來驗證此情況。

注意：一旦SolverManager存在，您不應該再需要大部分courseTimeTablingManager。