为什么调用 move.doMove(guiScoreDirector) 时 optaplanner 为空指针；

Question

我的 optaplanner 网络应用程序有问题。此应用程序基于 vehiclerouting 演示网络示例。我想在课程时间表的 Web 示例中实现手动 doChangeMove 函数。我的代码（courseTimeTablingManager.java）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();
}

每次我运行应用程序，它都会在函数 doMove 的 move.doMove(guiScoreDirector) 处崩溃。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

有人可以帮忙吗？提前致谢！

Answer 1

我假设实体（讲座？）为空。通过为 NullPointerException 添加调试断点来验证这一点。

注意：一旦 SolverManager 存在，您就不再需要大部分 courseTimeTablingManager。

为什么调用 move.doMove(guiScoreDirector) 时 optaplanner 为空指针；

Why optaplanner null pointer when calling move.doMove(guiScoreDirector);

java

web

optaplanner