de.csenk.gwt.commons.bean.shared.observe.impl.AbstractObservableProperty.java Source code

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Here is the source code for de.csenk.gwt.commons.bean.shared.observe.impl.AbstractObservableProperty.java

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/*
 * Copyright 2012 Christian Senk
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package de.csenk.gwt.commons.bean.shared.observe.impl;

import com.google.gwt.event.shared.GwtEvent;
import com.google.gwt.event.shared.HandlerManager;
import com.google.gwt.event.shared.HandlerRegistration;

import de.csenk.gwt.commons.bean.shared.observe.ObservableProperty;
import de.csenk.gwt.commons.bean.shared.observe.PropertyValueChangeEvent;
import de.csenk.gwt.commons.bean.shared.observe.PropertyValueChangeHandler;

/**
 * @author senk.christian@googlemail.com
 *
 */
public abstract class AbstractObservableProperty<V> implements ObservableProperty<V> {

    private final HandlerManager handlerManager;

    /**
     * 
     */
    public AbstractObservableProperty() {
        handlerManager = new HandlerManager(this);
    }

    /**
     * @param value
     */
    public abstract void setValue(V value);

    /**
     * @return
     */
    public abstract V getValue();

    /**
     * @param value
     */
    public void set(V value) {
        final V oldValue = getValue();
        setValue(value);

        if (!(oldValue == value || (oldValue != null && oldValue.equals(value))))
            fireEvent(new PropertyValueChangeEvent<V>(oldValue, value));
    }

    /**
     * @return
     */
    public V get() {
        return getValue();
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public HandlerRegistration addPropertyValueChangeHandler(PropertyValueChangeHandler<V> handler) {
        return handlerManager.addHandler(PropertyValueChangeEvent.getType(), handler);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void fireEvent(GwtEvent<?> event) {
        handlerManager.fireEvent(event);
    }

}