at.tugraz.kmi.medokyservice.fca.db.DataObject.java Source code

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Here is the source code for at.tugraz.kmi.medokyservice.fca.db.DataObject.java

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/*
 * 
 * MEDoKyService:
 * A web service component for learner modelling and learning recommendations.
 * Copyright (C) 2015 KTI, TUGraz, Contact: simone.kopeinik@tugraz.at
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; 
 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  
 * See the GNU Affero General Public License for more details.  
 * For more information about the GNU Affero General Public License see <http://www.gnu.org/licenses/>.
 * 
 */
package at.tugraz.kmi.medokyservice.fca.db;

import java.io.Serializable;

import at.tugraz.kmi.medokyservice.json.JSONMapper;

import com.google.gson.JsonObject;

/**
 * Root Class of all FCA related classes providing a {@link Long} id to store it
 * inside the {@link Database} and a {@link String} name and description.
 * 
 * @author Bernd Prnster <mail@berndpruenster.org>
 * 
 */
public abstract class DataObject implements Comparable<DataObject>, Serializable {

    private static final long serialVersionUID = 4030398877692134854L;
    /**
     * unique identifier of a {@link DataObject}
     */
    protected long id;
    private String name;
    private String description;

    /**
     * Creates a new {@link DataObject} with a unique {@literal id}
     * 
     * @param name
     *          the objects name
     * @param description
     *          the objects description
     */
    public DataObject(String name, String description) {
        this.id = IDGenerator.getInstance().getID();
        this.name = name;
        this.description = description;
    }

    public long getId() {
        return id;
    }

    public String getName() {
        if (name == null)
            return "UNDEFINED: " + id;
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    /**
     * Compares this {@link DataObject} with the specified {@link DataObject} for
     * order. Returns a negative integer, zero, or a positive integer as this
     * {@link DataObject}s id is less than, equal to, or greater than the
     * specified {@link DataObject}s id.
     * 
     * @see java.lang.Comparable#compareTo(Object)
     * 
     * @return a negative integer, zero, or a positive integer as this
     *         {@link DataObject}s id is less than, equal to, or greater than the
     *         specified {@link DataObject}s id.
     */
    @Override
    public int compareTo(DataObject o) {
        return (id < o.id) ? -1 : ((id == o.id) ? 0 : 1);
    }

    /**
     * Indicates whether some other object is "equal to" this one. If the other
     * object extends {@link DataObject} the ids are checked for eqaulity.
     * 
     * @see Object#equals(Object)
     * 
     * @param o
     *          the reference object with which to compare.
     * @throws NullPointerException
     *           when trying to compare this object to null.
     * @return {@literal true} if this object is the same as the {@literal obj}
     *         argument; {@literal false} otherwise.
     * 
     */
    @Override
    public boolean equals(Object o) {
        if (o == null)
            throw new NullPointerException("Error trying to compare a DataObject to null!");
        if (o instanceof DataObject)
            return id == ((DataObject) (o)).id;
        return o.equals(this);
    }

    @Override
    public int hashCode() {
        return (int) (id ^ (id >>> 32));
    }

    /**
     * Returns a JSON string representation of the object using the
     * {@link JSONMapper}
     * 
     * @return a JSON string representation of the object
     */
    @Override
    public String toString() {
        try {
            return JSONMapper.getInstance().toJson(this);
        } catch (Exception e) {
            JsonObject js = new JsonObject();
            js.addProperty("id", id);
            js.addProperty("name", name);
            js.addProperty("description", description);
            return js.toString();
        }

    }

}