Class ListSwapMove<Solution_>

  • Type Parameters:
    Solution_ - the solution type, the class with the PlanningSolution annotation
    All Implemented Interfaces:

    public class ListSwapMove<Solution_>
    extends AbstractMove<Solution_>
    Swaps two elements of a list variable. Each element is identified by an entity instance and an index in that entity's list variable. The swap move has two sides called left and right. The element at leftIndex in leftEntity's list variable is replaced by the element at rightIndex in rightEntity's list variable and vice versa. Left and right entity can be the same instance.

    An undo move is created by flipping the left and right-hand entity and index.

    • Constructor Detail

      • ListSwapMove

        public ListSwapMove​(ListVariableDescriptor<Solution_> variableDescriptor,
                            Object leftEntity,
                            int leftIndex,
                            Object rightEntity,
                            int rightIndex)
        Create a move that swaps a list variable element at leftEntity.listVariable[leftIndex] with rightEntity.listVariable[rightIndex].

        ListSwapMove anatomy

                                         ┌ rightEntity
                        right element ┐  │   ┌ rightIndex
                                      ↓  ↓   ↓
                       A {Ann[0]} <-> Y {Bob[1]}
                       ↑  ↑   ↑
          left element ┘  │   └ leftIndex
                          └ leftEntity


         Ann.tasks = [A, B, C]
         Bob.tasks = [X, Y]
         ListSwapMove: A {Ann[0]} <-> Y {Bob[1]}
         Ann.tasks = [Y, B, C]
         Bob.tasks = [X, A]
        variableDescriptor - descriptor of a list variable, for example Employee.taskList
        leftEntity - together with leftIndex identifies the left element to be moved
        leftIndex - together with leftEntity identifies the left element to be moved
        rightEntity - together with rightIndex identifies the right element to be moved
        rightIndex - together with rightEntity identifies the right element to be moved
    • Method Detail

      • getLeftEntity

        public Object getLeftEntity()
      • getLeftIndex

        public int getLeftIndex()
      • getRightEntity

        public Object getRightEntity()
      • getRightIndex

        public int getRightIndex()
      • getLeftValue

        public Object getLeftValue()
      • getRightValue

        public Object getRightValue()
      • isMoveDoable

        public boolean isMoveDoable​(ScoreDirector<Solution_> scoreDirector)
        Description copied from interface: Move
        Called before a move is evaluated to decide whether the move can be done and evaluated. A Move is not doable if:
        • Either doing it would change nothing in the PlanningSolution.
        • Either it's simply not possible to do (for example due to built-in hard constraints).

        It is recommended to keep this method implementation simple: do not use it in an attempt to satisfy normal hard and soft constraints.

        Although you could also filter out non-doable moves in for example the MoveSelector or MoveListFactory, this is not needed as the Solver will do it for you.

        scoreDirector - the ScoreDirector not yet modified by the move.
        true if the move achieves a change in the solution and the move is possible to do on the solution.
      • rebase

        public ListSwapMove<Solution_> rebase​(ScoreDirector<Solution_> destinationScoreDirector)
        Description copied from interface: Move
        Rebases a move from an origin ScoreDirector to another destination ScoreDirector which is usually on another Thread or JVM. The new move returned by this method translates the entities and problem facts to the destination PlanningSolution of the destination ScoreDirector, That destination PlanningSolution is a deep planning clone (or an even deeper clone) of the origin PlanningSolution that this move has been generated from.

        That new move does the exact same change as this move, resulting in the same PlanningSolution state, presuming that destination PlanningSolution was in the same state as the original PlanningSolution to begin with.

        Generally speaking, an implementation of this method iterates through every entity and fact instance in this move, translates each one to the destination ScoreDirector with ScoreDirector.lookUpWorkingObject(Object) and creates a new move instance of the same move type, using those translated instances.

        The destination PlanningSolution can be in a different state than the original PlanningSolution. So, rebasing can only depend on the identity of planning entities and planning facts, which is usually declared by a PlanningId on those classes. It must not depend on the state of the planning variables. One thread might rebase a move before, amid or after another thread does that same move instance.

        This method is thread-safe.

        destinationScoreDirector - never null, the ScoreDirector.getWorkingSolution() that the new move should change the planning entity instances of.
        never null, a new move that does the same change as this move on another solution instance
      • getSimpleMoveTypeDescription

        public String getSimpleMoveTypeDescription()
        Description copied from interface: Move
        Describes the move type for statistical purposes. For example "ChangeMove(".

        The format is not formalized. Never parse the String returned by this method.

        never null
      • hashCode

        public int hashCode()
        hashCode in class Object