ClassUtils.java :  » Report » jasperreports-3.7.2 » net » sf » jasperreports » engine » util » Java Open Source

/*
 * JasperReports - Free Java Reporting Library.
 * Copyright (C) 2001 - 2009 Jaspersoft Corporation. All rights reserved.
 * http://www.jaspersoft.com
 *
 * Unless you have purchased a commercial license agreement from Jaspersoft,
 * the following license terms apply:
 *
 * This program is part of JasperReports.
 *
 * JasperReports 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 3 of the License, or
 * (at your option) any later version.
 *
 * JasperReports 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 JasperReports. If not, see <http://www.gnu.org/licenses/>.
 */
package net.sf.jasperreports.engine.util;

import net.sf.jasperreports.engine.JRRuntimeException;

/**
 * Class utilities.
 * 
 * @author Lucian Chirita (lucianc@users.sourceforge.net)
 * @version $Id: ClassUtils.java 3712 2010-04-08 09:53:09Z teodord $
 */
public final class ClassUtils
{

  /**
   * Instantiates a class.
   * 
   * <p>
   * The class is expected to have a public no-argument constructor.
   * 
   * @param className the class name
   * @param expectedType the expected (super) type of the result
   * @return a newly created instance of the specified class
   * @throws JRRuntimeException if the class cannot be loaded or instantiated,
   * or if it does not implement the expected type
   */
  public static final Object instantiateClass(String className, Class expectedType)
  {
    try
    {
      Class clazz = JRClassLoader.loadClassForName(className);
      if (!expectedType.isAssignableFrom(clazz))
      {
        throw new JRRuntimeException("Class " + className 
            + " does not implement/extend " + expectedType.getName());
      }
      return clazz.newInstance();
    }
    catch (ClassNotFoundException e)
    {
      throw new JRRuntimeException(
          "Could not load class " + className, e);
    }
    catch (InstantiationException e)
    {
      throw new JRRuntimeException(
          "Could not instantiate class " + className, e);
    }
    catch (IllegalAccessException e)
    {
      throw new JRRuntimeException(
          "Could not instantiate class " + className, e);
    }
  }
  

  private ClassUtils()
  {
  }
}