InputObservable.java example

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package org.jowidgets.spi.impl.controller;

import java.util.LinkedHashSet;
import java.util.LinkedList;
import java.util.Set;

import org.jowidgets.common.widgets.controller.IInputListener;
import org.jowidgets.common.widgets.controller.IInputObservable;
import org.jowidgets.util.Assert;
import org.jowidgets.util.NullCompatibleEquivalence;

public class InputObservable implements IInputObservable {

    private final Set<IInputListener> inputListeners;

    private Object lastValue;

    public InputObservable() {
        this.inputListeners = new LinkedHashSet<IInputListener>();
    }

    @Override
    public final void addInputListener(final IInputListener listener) {
        Assert.paramNotNull(listener, "listener");
        this.inputListeners.add(listener);
    }

    @Override
    public final void removeInputListener(final IInputListener listener) {
        Assert.paramNotNull(listener, "listener");
        this.inputListeners.remove(listener);
    }

    public void fireInputChanged(final Object value) {
        if (!NullCompatibleEquivalence.equals(value, lastValue)) {
            for (final IInputListener inputListener : new LinkedList<IInputListener>(inputListeners)) {
                inputListener.inputChanged();
            }
            lastValue = value;
        }
    }

}