# Package org.optaplanner.core.impl.domain.variable.listener

- Interface Summary
  Interface | Description
  --- | ---
  SourcedVariableListener<Entity_> | Often used to externalize data for a `Supply` from the domain model itself.
  StatefulVariableListener<Entity_> | Deprecated. `VariableListener` can now be stateful too.
  VariableListener<Entity_> | Deprecated. in favor of `VariableListener`

- Class Summary
  Class | Description
  --- | ---
  VariableListenerAdapter<Entity_> | Deprecated.