de.openknowledge.domain.AbstractSimpleValueObject.java Source code

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Here is the source code for de.openknowledge.domain.AbstractSimpleValueObject.java

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/*
 * Copyright (C) Arne Limburg
 *
 * 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.openknowledge.domain;

import static org.apache.commons.lang3.Validate.notNull;

import java.io.Serializable;

import javax.persistence.Access;
import javax.persistence.AccessType;
import javax.persistence.MappedSuperclass;

/**
 * A base class for value object that contain one simple value.
 * 
 * @author Arne Limburg - open knowledge GmbH
 */
@MappedSuperclass
@Access(AccessType.FIELD)
public abstract class AbstractSimpleValueObject<V extends Comparable<V>>
        implements Serializable, Comparable<AbstractSimpleValueObject<V>> {

    private V value;

    protected AbstractSimpleValueObject() {
        // for subclassing
    }

    public AbstractSimpleValueObject(V value) {
        this.value = validate(value);
    }

    /**
     * Validation and normalization callback used during construction of the value object. Subclasses may override this
     * method to alter validation and normalization.
     *
     * @param parameterValue The constructor value.
     * @return The validated and normalized value.
     */
    protected V validate(V parameterValue) {
        return notNull(parameterValue, "value must not be null");
    }

    protected V getValue() {
        return value;
    }

    @Override
    public String toString() {
        return getValue().toString();
    }

    @Override
    public int hashCode() {
        return getValue().hashCode();
    }

    @Override
    public boolean equals(Object object) {
        if (this == object) {
            return true;
        }
        if (object == null || !(object.getClass().isAssignableFrom(getClass())
                || getClass().isAssignableFrom(object.getClass()))) {
            return false;
        }
        AbstractSimpleValueObject<V> valueObject = (AbstractSimpleValueObject<V>) object;
        return valueObject.getValue().equals(getValue());
    }

    @Override
    public int compareTo(AbstractSimpleValueObject<V> object) {
        return getValue().compareTo(object.getValue());
    }
}