Package com.graphhopper.jsprit.core.algorithm.listener

Interface AlgorithmEventListener

Functional Interface:
This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.
@FunctionalInterface public interface AlgorithmEventListener
Listener interface for receiving algorithm events.

Implement this interface to receive notifications about all events that occur during algorithm execution. Use pattern matching on the sealed AlgorithmEvent hierarchy to handle specific event types.

Example usage:


 algorithm.addEventListener(event -> {
     switch (event) {
         case IterationStarted e -> System.out.println("Starting iteration " + e.iteration());
         case JobInserted e -> System.out.println("Job " + e.job().getId() + " inserted into " + e.routeId());
         case AcceptanceDecision e -> {
             if (e.isNewBest()) {
                 System.out.println("New best solution: " + e.newCost());
             }
         }
         default -> {} // ignore other events
     }
 });

For filtering specific event types, you can also use:


 algorithm.addEventListener(AlgorithmEventListener.forType(JobInserted.class, e -> {
     System.out.println("Job inserted: " + e.job().getId());
 }));

  • Method Details

    • onEvent

      void onEvent(AlgorithmEvent event)
      Called when an algorithm event occurs.
      Parameters:
      event - The event that occurred

    • forType

      static <T extends AlgorithmEvent> AlgorithmEventListener forType(Class<T> eventType, Consumer<T> handler)
      Creates a listener that only handles events of a specific type.
      Type Parameters:
      T - The event type
      Parameters:
      eventType - The type of events to handle
      handler - The handler for events of this type
      Returns:
      A listener that filters and handles only the specified event type

    • composite

      static AlgorithmEventListener composite(AlgorithmEventListener... listeners)
      Creates a composite listener that forwards events to multiple listeners.
      Parameters:
      listeners - The listeners to forward events to
      Returns:
      A composite listener