org.optaplanner.core.impl.heuristic.selector.move.generic

## Class SwapMove<Solution_>

- java.lang.Object
- - org.optaplanner.core.impl.heuristic.move.AbstractMove<Solution_>
  - - org.optaplanner.core.impl.heuristic.selector.move.generic.SwapMove<Solution_>

- Type Parameters:
    `Solution_` - the solution type, the class with the `PlanningSolution` annotation
  All Implemented Interfaces:
    Move<Solution_>
  Direct Known Subclasses:
    ChainedSwapMove

      public class SwapMove<Solution_>
      extends AbstractMove<Solution_>

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `protected Object` | `leftEntity`
    `protected Object` | `rightEntity`
    `protected List<GenuineVariableDescriptor<Solution_>>` | `variableDescriptorList`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `SwapMove(List<GenuineVariableDescriptor<Solution_>> variableDescriptorList, Object leftEntity, Object rightEntity)`

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `protected void` | `appendVariablesToString(StringBuilder s, Object entity)`
    `SwapMove<Solution_>` | `createUndoMove(ScoreDirector<Solution_> scoreDirector)` Called before the move is done, so the move can be evaluated and then be undone without resulting into a permanent change in the solution.
    `protected void` | `doMoveOnGenuineVariables(ScoreDirector<Solution_> scoreDirector)` Like `AbstractMove.doMove(ScoreDirector)` but without the `ScoreDirector.triggerVariableListeners()` call (because `AbstractMove.doMove(ScoreDirector)` already does that).
    `boolean` | `equals(Object o)`
    `Object` | `getLeftEntity()`
    `Collection<? extends Object>` | `getPlanningEntities()` Returns all planning entities that are being changed by this move.
    `Collection<? extends Object>` | `getPlanningValues()` Returns all planning values that entities are being assigned to by this move.
    `Object` | `getRightEntity()`
    `String` | `getSimpleMoveTypeDescription()` Describes the move type for statistical purposes.
    `List<String>` | `getVariableNameList()`
    `int` | `hashCode()`
    `boolean` | `isMoveDoable(ScoreDirector<Solution_> scoreDirector)` Called before a move is evaluated to decide whether the move can be done and evaluated.
    `SwapMove<Solution_>` | `rebase(ScoreDirector<Solution_> destinationScoreDirector)` Rebases a move from an origin `ScoreDirector` to another destination `ScoreDirector` which is usually on another `Thread` or JVM.
    `String` | `toString()`

    - ### Methods inherited from class org.optaplanner.core.impl.heuristic.move.AbstractMove

      `doMove, rebaseArray, rebaseList`

    - ### Methods inherited from class java.lang.Object

      `clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

- - ### Field Detail

    - #### variableDescriptorList

          protected final List<GenuineVariableDescriptor<Solution_>> variableDescriptorList

    - #### leftEntity

          protected final Object leftEntity

    - #### rightEntity

          protected final Object rightEntity

  - ### Constructor Detail

    - #### SwapMove

          public SwapMove(List<GenuineVariableDescriptor<Solution_>> variableDescriptorList,
                          Object leftEntity,
                          Object rightEntity)

  - ### Method Detail

    - #### getVariableNameList

          public List<String> getVariableNameList()

    - #### getLeftEntity

          public Object getLeftEntity()

    - #### getRightEntity

          public Object getRightEntity()

    - #### 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.

      Parameters:
        `scoreDirector` - the `ScoreDirector` not yet modified by the move.
      Returns:
        true if the move achieves a change in the solution and the move is possible to do on the solution.

    - #### createUndoMove

          public SwapMove<Solution_> createUndoMove(ScoreDirector<Solution_> scoreDirector)

      Description copied from class: `AbstractMove`
      Called before the move is done, so the move can be evaluated and then be undone without resulting into a permanent change in the solution.
      Specified by:
        `createUndoMove` in class `AbstractMove<Solution_>`
      Parameters:
        `scoreDirector` - the `ScoreDirector` not yet modified by the move.
      Returns:
        an undoMove which does the exact opposite of this move.

    - #### rebase

          public SwapMove<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.

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

    - #### doMoveOnGenuineVariables

          protected void doMoveOnGenuineVariables(ScoreDirector<Solution_> scoreDirector)

      Description copied from class: `AbstractMove`
      Like `AbstractMove.doMove(ScoreDirector)` but without the `ScoreDirector.triggerVariableListeners()` call (because `AbstractMove.doMove(ScoreDirector)` already does that).
      Specified by:
        `doMoveOnGenuineVariables` in class `AbstractMove<Solution_>`
      Parameters:
        `scoreDirector` - never null

    - #### getSimpleMoveTypeDescription

          public String getSimpleMoveTypeDescription()

      Description copied from interface: `Move`
      Describes the move type for statistical purposes. For example "ChangeMove(Process.computer)".

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

      Returns:
        never null

    - #### getPlanningEntities

          public Collection<? extends Object> getPlanningEntities()

      Description copied from interface: `Move`
      Returns all planning entities that are being changed by this move. Required for `AcceptorType.ENTITY_TABU`.

      This method is only called after `Move.doMove(ScoreDirector)` (which might affect the return values).

      Duplicate entries in the returned `Collection` are best avoided. The returned `Collection` is recommended to be in a stable order. For example: use `List` or `LinkedHashSet`, but not `HashSet`.

      Returns:
        never null

    - #### getPlanningValues

          public Collection<? extends Object> getPlanningValues()

      Description copied from interface: `Move`
      Returns all planning values that entities are being assigned to by this move. Required for `AcceptorType.VALUE_TABU`.

      This method is only called after `Move.doMove(ScoreDirector)` (which might affect the return values).

      Duplicate entries in the returned `Collection` are best avoided. The returned `Collection` is recommended to be in a stable order. For example: use `List` or `LinkedHashSet`, but not `HashSet`.

      Returns:
        never null

    - #### equals

          public boolean equals(Object o)

      Overrides:
        `equals` in class `Object`

    - #### hashCode

          public int hashCode()

      Overrides:
        `hashCode` in class `Object`

    - #### toString

          public String toString()

      Overrides:
        `toString` in class `Object`

    - #### appendVariablesToString

          protected void appendVariablesToString(StringBuilder s,
                                                 Object entity)

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