Module is.codion.common.reactive
Package is.codion.common.reactive.observer

Class DefaultObserver<T>

java.lang.Object
is.codion.common.reactive.observer.DefaultObserver<T>
All Implemented Interfaces:
Observer<T>
public class DefaultObserver<T> extends Object implements Observer<T>
Thread-safe implementation of Observer. All listener management operations are synchronized using an internal lock. Dead weak references are cleaned up during add/remove operations.

  • Constructor Details

    • DefaultObserver

      protected DefaultObserver()
      Instantiates a new DefaultObserver

  • Method Details

    • addListener

      public final boolean addListener(Runnable runnable)
      Description copied from interface: Observer
      Adds listener to this Observer. Adding the same listener a second time has no effect.
      Specified by:
      addListener in interface Observer<T>
      Parameters:
      runnable - the listener to add
      Returns:
      true if this observer did not already contain the specified listener

    • removeListener

      public final boolean removeListener(Runnable runnable)
      Description copied from interface: Observer
      Removes listener from this Observer
      Specified by:
      removeListener in interface Observer<T>
      Parameters:
      runnable - the listener to remove
      Returns:
      true if this observer contained the specified listener

    • addConsumer

      public final boolean addConsumer(Consumer<? super T> consumer)
      Description copied from interface: Observer
      Adds consumer to this Observer. Adding the same consumer a second time has no effect.
      Specified by:
      addConsumer in interface Observer<T>
      Parameters:
      consumer - the consumer to add
      Returns:
      true if this observer did not already contain the specified consumer

    • removeConsumer

      public final boolean removeConsumer(Consumer<? super T> consumer)
      Description copied from interface: Observer
      Removes consumer from this Observer
      Specified by:
      removeConsumer in interface Observer<T>
      Parameters:
      consumer - the consumer to remove
      Returns:
      true if this observer contained the specified consumer

    • addWeakListener

      public final boolean addWeakListener(Runnable runnable)
      Description copied from interface: Observer
      Uses a WeakReference, adding listener does not prevent it from being garbage collected. Adding the same listener a second time has no effect.

      Note: Dead weak references accumulate until cleaned up, which happens automatically when listeners are added or removed. To trigger cleanup manually without modifying the listener set, call Observer.removeWeakListener(Runnable) with any non-existing listener: 

       // Clean up dead weak references
 observer.removeWeakListener(() -> {});
      Specified by:
      addWeakListener in interface Observer<T>
      Parameters:
      runnable - the listener
      Returns:
      true if this observer did not already contain the specified listener

    • removeWeakListener

      public final boolean removeWeakListener(Runnable runnable)
      Description copied from interface: Observer
      Removes listener from this Observer
      Specified by:
      removeWeakListener in interface Observer<T>
      Parameters:
      runnable - the listener to remove
      Returns:
      true if this observer contained the specified listener

    • addWeakConsumer

      public final boolean addWeakConsumer(Consumer<? super T> consumer)
      Description copied from interface: Observer
      Uses a WeakReference, adding consumer does not prevent it from being garbage collected. Adding the same consumer a second time has no effect.

      Note: Dead weak references accumulate until cleaned up, which happens automatically when listeners are added or removed. To trigger cleanup manually without modifying the listener set, call Observer.removeWeakConsumer(Consumer) with any non-existing consumer: 

       // Clean up dead weak references
 observer.removeWeakConsumer(data -> {});
      Specified by:
      addWeakConsumer in interface Observer<T>
      Parameters:
      consumer - the consumer
      Returns:
      true if this observer did not already contain the specified consumer

    • removeWeakConsumer

      public final boolean removeWeakConsumer(Consumer<? super T> consumer)
      Description copied from interface: Observer
      Removes consumer from this Observer.
      Specified by:
      removeWeakConsumer in interface Observer<T>
      Parameters:
      consumer - the consumer to remove
      Returns:
      true if this observer contained the specified consumer

    • when

      public final Observer<T> when(@Nullable T value)
      Description copied from interface: Observer
      Returns a new conditional Observer notified when this observer instance is triggered with the given value
      Specified by:
      when in interface Observer<T>
      Parameters:
      value - the value on which to trigger the observer
      Returns:
      a new conditional Observer

    • when

      public final Observer<T> when(Predicate<? super T> predicate)
      Description copied from interface: Observer
      Returns a new conditional Observer notified when this observer instance is triggered with a value satisfying the given predicate
      Specified by:
      when in interface Observer<T>
      Parameters:
      predicate - the predicate on which to trigger the observer
      Returns:
      a new conditional Observer

    • notifyListeners

      protected final void notifyListeners(@Nullable T data)
      Notifies all consumers and listeners
      Parameters:
      data - the data to propagate to consumers