AliasedDatabaseTable.java

/**
 * C-JDBC: Clustered JDBC.
 * Copyright (C) 2002-2004 French National Institute For Research In Computer
 * Science And Control (INRIA).
 * Contact: c-jdbc@objectweb.org
 * 
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by the
 * Free Software Foundation; either version 2.1 of the License, or any later
 * version.
 * 
 * This library 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 Lesser General Public License
 * for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 *
 * Initial developer(s): Emmanuel Cecchet.
 * Contributor(s): ______________________________________.
 */

package org.objectweb.cjdbc.common.sql.schema;

import java.io.Serializable;

/**
 * An <code>AliasedDatabaseTable</code> represents a database table with an
 * alias name. Example:
 * 
 * <pre>
 *  SELECT x.price FROM item x
 * </pre>
 * 
 * 
 * <p>
 * In this case, the <code>item</code> table has an alias named <code>x</code>.
 * 
 * @author <a href="mailto:Emmanuel.Cecchet@inria.fr">Emmanuel Cecchet</a>
 * @version 1.0
 */
public class AliasedDatabaseTable implements Serializable
{
  /** Database table. */
  private DatabaseTable table;

  /** Alias name or <code>null</code> if no alias is defined. */
  private String alias;

  /**
   * Creates a new <code>AliasedDatabaseTable</code> instance.
   * 
   * @param table a <code>DatabaseTable</code> value
   * @param alias the alias name, <code>null</code> if no alias is defined
   */
  public AliasedDatabaseTable(DatabaseTable table, String alias)
  {
    if (table == null)
      throw new IllegalArgumentException("Illegal null database table in AliasedDatabaseTable constructor");

    this.table = table;
    this.alias = alias;
  }

  /**
   * Returns the <code>DatabaseTable</code> object corresponding to this
   * database.
   * 
   * @return a <code>DatabaseTable</code> value
   */
  public DatabaseTable getTable()
  {
    return table;
  }

  /**
   * Gets the alias name.
   * 
   * @return the alias name. Returns <code>null</code> if no alias is set.
   */
  public String getAlias()
  {
    return alias;
  }

  /**
   * Two <code>AliasedDatabaseTable</code> are considered equal if they
   * represent the same table and have the same alias.
   * 
   * @param other the object to compare with
   * @return true if the 2 objects are the same
   */
  public boolean equals(Object other)
  {
    if ((other == null) || !(other instanceof AliasedDatabaseTable))
      return false;

    AliasedDatabaseTable ad = (AliasedDatabaseTable) other;
    if (alias == null)
      return (ad.getAlias() == null) && table.equals(ad.getTable());
    else
      return alias.equals(ad.getAlias()) && table.equals(ad.getTable());
  }
}

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