Package org.optaplanner.core.api.domain.variable

## Annotation Type PlanningVariable

-     @Target({METHOD,FIELD})
      @Retention(RUNTIME)
      public @interface PlanningVariable

  Specifies that a bean property (or a field) can be changed and should be optimized by the optimization algorithms.

  It is specified on a getter of a java bean property (or directly on a field) of a `PlanningEntity` class.

- - ### Optional Element Summary

    Optional Elements
    Modifier and Type | Optional Element | Description
    --- | --- | ---
    `PlanningVariableGraphType` | `graphType` | In some use cases, such as Vehicle Routing, planning entities form a specific graph type, as specified by `PlanningVariableGraphType`.
    `boolean` | `nullable` | A nullable planning variable will automatically add the planning value null to the `ValueRangeProvider`'s range.
    `Class<? extends SelectionFilter>` | `reinitializeVariableEntityFilter` | Deprecated. for removal.
    `Class<? extends Comparator>` | `strengthComparatorClass` | Allows a collection of planning values for this variable to be sorted by strength.
    `Class<? extends SelectionSorterWeightFactory>` | `strengthWeightFactoryClass` | The `SelectionSorterWeightFactory` alternative for `strengthComparatorClass()`.
    `String[]` | `valueRangeProviderRefs` | Any `ValueRangeProvider` annotation on a `PlanningSolution` or `PlanningEntity` will automatically be registered with its `ValueRangeProvider.id()`.

- - ### Element Detail

    - #### valueRangeProviderRefs

          String[] valueRangeProviderRefs

      Any `ValueRangeProvider` annotation on a `PlanningSolution` or `PlanningEntity` will automatically be registered with its `ValueRangeProvider.id()`.

      There should be at least 1 element in this array.

      Returns:
        1 (or more) registered `ValueRangeProvider.id()`
      Default:
        {}

  - - #### nullable

          boolean nullable

      A nullable planning variable will automatically add the planning value null to the `ValueRangeProvider`'s range.

      In repeated planning use cases, it's recommended to specify a `reinitializeVariableEntityFilter()` for every nullable planning variable too.

      Nullable true is not compatible with `PlanningVariableGraphType.CHAINED` true. Nullable true is not compatible with a primitive property type.

      Returns:
        true if null is a valid value for this planning variable
      Default:
        false

  - - #### reinitializeVariableEntityFilter

          @Deprecated
          Class<? extends SelectionFilter> reinitializeVariableEntityFilter

      Deprecated.
      for removal. Instead, filter the entity selector of the placer in the construction heuristic.
      Construction heuristics only change reinitializable planning variables. Non reinitializable planning variable is ignored by construction heuristics. This is especially useful in repeated planning use cases, in which starting from scratch would waste previous results and time.

      If no reinitializeVariableEntityFilter is specified, the default considers an entity uninitialized for a variable if its value is null (even if `nullable()` is true).

      The method `SelectionFilter.accept(ScoreDirector, Object)` returns false if the selection entity should be reinitialized for this variable and it returns true if the selection entity should not be reinitialized for this variable

      Returns:
        `PlanningVariable.NullReinitializeVariableEntityFilter` when it is null (workaround for annotation limitation)
      Default:
        org.optaplanner.core.api.domain.variable.PlanningVariable.NullReinitializeVariableEntityFilter.class

  - - #### graphType

          PlanningVariableGraphType graphType

      In some use cases, such as Vehicle Routing, planning entities form a specific graph type, as specified by `PlanningVariableGraphType`.
      Returns:
        never null, defaults to `PlanningVariableGraphType.NONE`
      Default:
        org.optaplanner.core.api.domain.variable.PlanningVariableGraphType.NONE

  - - #### strengthComparatorClass

          Class<? extends Comparator> strengthComparatorClass

      Allows a collection of planning values for this variable to be sorted by strength. A strengthWeight estimates how strong a planning value is. Some algorithms benefit from planning on weaker planning values first or from focusing on them.

      The `Comparator` should sort in ascending strength. For example: sorting 3 computers on strength based on their RAM capacity: Computer B (1GB RAM), Computer A (2GB RAM), Computer C (7GB RAM),

      Do not use together with `strengthWeightFactoryClass()`.

      Returns:
        `PlanningVariable.NullStrengthComparator` when it is null (workaround for annotation limitation)
      See Also:
        `strengthWeightFactoryClass()`
      Default:
        org.optaplanner.core.api.domain.variable.PlanningVariable.NullStrengthComparator.class

  - - #### strengthWeightFactoryClass

          Class<? extends SelectionSorterWeightFactory> strengthWeightFactoryClass

      The `SelectionSorterWeightFactory` alternative for `strengthComparatorClass()`.

      Do not use together with `strengthComparatorClass()`.

      Returns:
        `PlanningVariable.NullStrengthWeightFactory` when it is null (workaround for annotation limitation)
      See Also:
        `strengthComparatorClass()`
      Default:
        org.optaplanner.core.api.domain.variable.PlanningVariable.NullStrengthWeightFactory.class