Package com.vaadin.flow.signals.impl

Class Effect

java.lang.Object
com.vaadin.flow.signals.impl.Effect
All Implemented Interfaces:
Serializable
public class Effect extends Object implements Serializable
Applies a side effect based on signal value changes. An effect is a callback that is initially run when the effect is created, and subsequently run again whenever any dependency changes. Dependencies are automatically registered for all signals that are read from the callback. The callback is run again whenever there's a change to any dependency. Dependencies are always updated based the signals read during the most recent invocation.
See Also:

  • Constructor Details

    • Effect

      public Effect(EffectAction action)
      Creates a signal effect with the given action and the default dispatcher. The action is run when the effect is created and is subsequently run again whenever there's a change to any signal value that was read during the last invocation.
      Parameters:
      action - the action to use, not null
      See Also:

    • Effect

      public Effect(EffectAction action, SerializableExecutor dispatcher)
      Creates a signal effect with the given action and a custom dispatcher. The action is run when the effect is created and is subsequently run again whenever there's a change to any signal value that was read during the last invocation. The dispatcher can be used to make sure changes are evaluated asynchronously or with some specific context available. The action itself needs to be synchronous to be able to track changes.
      Parameters:
      action - the action to use, not null
      dispatcher - the dispatcher to use when handling changes, not null

  • Method Details

    • dispose

      public void dispose()
      Disposes this effect by unregistering all current dependencies and preventing the action from running again.

    • effect

      public static <C extends Component> Registration effect(C owner, SerializableRunnable effectFunction)
      Creates a Signal effect that is owned by a given component. The effect is enabled when the component is attached and automatically disabled when it is detached.

      Example of usage: 

       Registration effect = Effect.effect(myComponent, () -> {
     Notification.show("Component is attached and signal value is "
             + someSignal.get());
 });
 effect.remove(); // to remove the effect when no longer needed
      Type Parameters:
      C - the type of the component
      Parameters:
      owner - the owner component for which the effect is applied, must not be null
      effectFunction - the effect function to be executed when any dependency is changed, must not be null
      Returns:
      a Registration that can be used to remove the effect function