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From bay...@apache.org
Subject cvs commit: jakarta-commons/lang/src/java/org/apache/commons/lang ClassUtils.java
Date Wed, 14 Aug 2002 04:51:28 GMT
bayard      2002/08/13 21:51:28

  Added:       lang/src/java/org/apache/commons/lang ClassUtils.java
  Log:
  Checked back in for consideration in 1.0
  
  Revision  Changes    Path
  1.1                  jakarta-commons/lang/src/java/org/apache/commons/lang/ClassUtils.java
  
  Index: ClassUtils.java
  ===================================================================
  package org.apache.commons.lang;
  
  /* ====================================================================
   * The Apache Software License, Version 1.1
   *
   * Copyright (c) 2002 The Apache Software Foundation.  All rights
   * reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   *
   * 3. The end-user documentation included with the redistribution, if
   *    any, must include the following acknowlegement:
   *       "This product includes software developed by the
   *        Apache Software Foundation (http://www.apache.org/)."
   *    Alternately, this acknowlegement may appear in the software itself,
   *    if and wherever such third-party acknowlegements normally appear.
   *
   * 4. The names "The Jakarta Project", "Commons", and "Apache Software
   *    Foundation" must not be used to endorse or promote products derived
   *    from this software without prior written permission. For written
   *    permission, please contact apache@apache.org.
   *
   * 5. Products derived from this software may not be called "Apache"
   *    nor may "Apache" appear in their names without prior written
   *    permission of the Apache Software Foundation.
   *
   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   */
  
  /**
   * A set of static utilities for use with ClassUtils.
   *
   * @author  bayard@generationjava.com
   * @version $Id: ClassUtils.java,v 1.1 2002/08/14 04:51:28 bayard Exp $
   */
  final public class ClassUtils {
  
      /**
       * Create an object from the classname. Must have an empty constructor.
       *
       * @param classname String name of the class
       *
       * @return Object instance of the class or null
       */
      static public Object createObject(String classname) {
          Class tmpClass = null;
  
          tmpClass = getClass(classname);
  
          return createObject(tmpClass);
      }
  
      /**
       * Create an object from a class. 
       *
       * @param clss Class object to instantiate
       *
       * @return Object instance of the class or null
       */
      static public Object createObject(Class clss) {
  
          try {
              return clss.newInstance();
          } catch (IllegalAccessException  iae) {
              System.err.println("Cant instantiate " + clss.getName() + " because " +
                     iae.getMessage());
          } catch (InstantiationException  ie) {
              System.err.println("Cant instantiate " + clss.getName() + " because " +
                     ie.getMessage());
          }
  
          return null;
      }
  
      /**
       * Is this Class in the CLASSPATH
       *
       * @param classname String of the class
       *
       * @return boolean exists or not.
       */
      static public boolean classExists(String classname) {
          Class tmpClass = null;
  
          /* try and load class */
          try {
              tmpClass = Class.forName(classname);
          } catch (ClassNotFoundException cnfe) {
              return false;
          } catch (IllegalArgumentException iae) {
              return false;
          }
       
          return true;   
      }
  
      /**
       * Get the Class object for a classname.
       *
       * @param classname String of the class
       *
       * @return Class instance for the class.
       */
      static public Class getClass(String classname) {
          Class tmpClass = null;
  
          /* try an load class */
          try {
              tmpClass = Class.forName(classname);
          } catch (ClassNotFoundException cnfe) {
              System.out.println("Can't resolve classname " + classname);
          } catch (IllegalArgumentException iae) {
              System.err.println("Cant resolve " + tmpClass.getName() + " because " + iae.getMessage());
          }
       
          return tmpClass;   
      }
  
      /**
       * Is this Class object an instance of the class with this name.
       *
       * @param clss Class instance
       * @param inst String name of potential supertype
       *
       * @return boolean was it an instanceof
       */
      static public boolean classInstanceOf(Class clss, String inst) {
          if(classImplements(clss,inst)) {
              return true;
          } else
          if(classExtends(clss,inst)) {
              return true;
          } else {
              return false;
          }
      }
  
      /**
       * Does this Class implement an interface with this name.
       *
       * @param clss Class instance
       * @param exts String name of potential interface
       *
       * @return boolean was it an implementor
       */
      static public boolean classImplements(Class clss, String exts) {
  
        Class sprcls = clss;
        Class excls  = getClass(exts);
  
        while(sprcls != null) {
          Class[] interfaces = sprcls.getInterfaces();
  
          for(int i=0;i<interfaces.length;i++) {
              if(interfaces[i].equals(excls)) {
                  return true;
              }
          }
  
          sprcls = sprcls.getSuperclass();
        }
  
        return false;
      }
  
      /**
       * Does this Class extend a superclass with this name.
       *
       * @param clss Class instance
       * @param exts String name of potential superclass
       *
       * @return boolean was it a superclass
       */
      static public boolean classExtends(Class clss, String exts) {
          if(clss == null) {
              return false;
          }
          if(clss.getName().equals(exts)) {
              return true;
          }
          Class sprcls = clss.getSuperclass();
          Class excls = getClass(exts);
  
  //        while(! sprcls.equals(sprcls.getSuperclass()) ) {
          while( sprcls != null ) {
              if(sprcls.equals(excls)) {
                  return true;
              }
              sprcls = sprcls.getSuperclass();
          }
          return false;
      }
  
  }
  
  
  

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