# UpdateListenerCollection.java

    package org.codefilarete.stalactite.engine.listener;

    import java.util.ArrayList;
    import java.util.List;

    import org.codefilarete.tool.Duo;

    /**
     * @author Guillaume Mary
     */
    public class UpdateListenerCollection<E> implements UpdateListener<E> {

    	private final List<UpdateListener<E>> updateListeners = new ArrayList<>();

    	@Override
    	public void beforeUpdate(Iterable<? extends Duo<E, E>> updatePayloads, boolean allColumnsStatement) {
    		updateListeners.forEach(listener -> listener.beforeUpdate(updatePayloads, allColumnsStatement));
    	}

    	@Override
    	public void afterUpdate(Iterable<? extends Duo<E, E>> entities, boolean allColumnsStatement) {
    		updateListeners.forEach(listener -> listener.afterUpdate(entities, allColumnsStatement));
    	}

    	@Override
    	public void onUpdateError(Iterable<? extends E> entities, RuntimeException runtimeException) {
    		updateListeners.forEach(listener -> listener.onUpdateError(entities, runtimeException));
    	}

    	public void add(UpdateListener<E> updateListener) {
    		this.updateListeners.add(updateListener);
    	}

    	/**
    	 * Move internal listeners to given instance.
    	 * Useful to aggregate listeners into a single instance.
    	 * Please note that as this method is named "move" it means that listeners of current instance will be cleared.
    	 *
    	 * @param updateListener the target listener on which the one of current instance must be moved to.
    	 */
    	public void moveTo(UpdateListenerCollection<E> updateListener) {
    		updateListener.updateListeners.addAll(this.updateListeners);
    		this.updateListeners.clear();
    	}

    }