Optaplanner：selectionList包含2次相同的selection

Question

我是 optplanner 的新手，正在尝试使用它来解决时间表问题，但是在完成所有设置后，当我尝试解决问题时，出现以下错误：

java.lang.IllegalStateException: The selectionList contains 2 times the same selection (c0001{t000}-0 @ null + null) and (c0001{t000}-1 @ null + null).
    at org.optaplanner.core.impl.heuristic.selector.common.decorator.WeightFactorySelectionSorter.sort(WeightFactorySelectionSorter.java:58)
    at org.optaplanner.core.impl.heuristic.selector.entity.decorator.SortingEntitySelector.constructCache(SortingEntitySelector.java:44)
    at org.optaplanner.core.impl.heuristic.selector.common.SelectionCacheLifecycleBridge.phaseStarted(SelectionCacheLifecycleBridge.java:49)
    at org.optaplanner.core.impl.phase.event.PhaseLifecycleSupport.firePhaseStarted(PhaseLifecycleSupport.java:39)
    at org.optaplanner.core.impl.heuristic.selector.AbstractSelector.phaseStarted(AbstractSelector.java:47)
    at org.optaplanner.core.impl.phase.event.PhaseLifecycleSupport.firePhaseStarted(PhaseLifecycleSupport.java:39)
    at org.optaplanner.core.impl.heuristic.selector.AbstractSelector.phaseStarted(AbstractSelector.java:47)
    at org.optaplanner.core.impl.phase.event.PhaseLifecycleSupport.firePhaseStarted(PhaseLifecycleSupport.java:39)
    at org.optaplanner.core.impl.constructionheuristic.placer.AbstractEntityPlacer.phaseStarted(AbstractEntityPlacer.java:41)
    at org.optaplanner.core.impl.constructionheuristic.DefaultConstructionHeuristicPhase.phaseStarted(DefaultConstructionHeuristicPhase.java:124)
    at org.optaplanner.core.impl.constructionheuristic.DefaultConstructionHeuristicPhase.solve(DefaultConstructionHeuristicPhase.java:67)
    at org.optaplanner.core.impl.solver.DefaultSolver.runPhases(DefaultSolver.java:214)
    at org.optaplanner.core.impl.solver.DefaultSolver.solve(DefaultSolver.java:176)

以前有没有人遇到过这个问题，如果遇到过请帮忙。

Answer 1

您的数据集（或域对象的 equals() 方法）似乎有问题。

The selectionList contains 2 times the same selection (c0001{t000}-0 @ null + null) and (c0001{t000}-1 @ null + null).

认为这2讲是一样的：

c0001...-0 // 第 0 课当然是 0001
c0001...-1 // 第 1 课当然是 0001

显然他们不相等，因为他们有不同的lectureIndexInCourse。

Lecture 继承了 AbstractPersistable 的 equals 方法，该方法基于 id 进行相等处理。

我敢打赌，您的数据集中的讲座 ID 为空或重复。

Optaplanner：selectionList包含2次相同的selection

Optaplanner: The selectionList contains 2 times the same selection

constraints

optaplanner