/*
 *     file: DynamicTypeChecking.java
 *  package: oreilly.hcj.reflection
 *
 * This software is granted under the terms of the Common Public License,
 * CPL, which may be found at the following URL:
 * http://www-124.ibm.com/developerworks/oss/CPLv1.0.htm
 *
 * Copyright(c) 2003-2005 by the authors indicated in the @author tags.
 * All Rights are Reserved by the various authors.
 *
########## DO NOT EDIT ABOVE THIS LINE ########## */

package oreilly.hcj.reflection;

import java.util.Iterator;
import java.util.Set;

/**  
 * Demonstrates Dynamic class type checking.
 *
 * @author <a href=mailto:kraythe@arcor.de>Robert Simmons jr. (kraythe)</a>
 * @version $Revision: 1.3 $
 */
public class DynamicTypeChecking {
	/** 
	 * Demonstrates usage of <tt>isAssignableFrom</tt> on a class object.
	 *
	 * @param dataType The data type to check.
	 *
	 * @return The value <tt>true</tt> if the class is a descendant of
	 *         <tt>java.lang.Number</tt> or <tt>false</tt> if it isnt.
	 */
	public static boolean isNumber(final Class dataType) {
		return Number.class.isAssignableFrom(dataType);
	}

	/** 
	 * Demonstration Method.
	 *
	 * @param args Command Line arguments.
	 */
	public static void main(final String[] args) {
		System.out.println("Using isAssignableFrom:");
		useAssignable(InstanceOfDemo.OBJECT_SET);
		System.out.println("\nUsing isInstance:");
		useIsInstance(InstanceOfDemo.OBJECT_SET);
	}

	/** 
	 * Demonstrates use of <tt>isAssignableFrom</tt> on objects in a set.
	 *
	 * @param inputSet The set to check.
	 */
	public static void useAssignable(final Set inputSet) {
		final Iterator iter = inputSet.iterator();
		Object obj = null;

		while (iter.hasNext()) {
			obj = iter.next();
			if (obj != null) {
				if (Number.class.isAssignableFrom(obj.getClass())) {
					System.out.println(obj);
				}
			}
		}
	}

	/** 
	 * Demonstrates usage of <tt>isInstance</tt> on objects in a set.
	 *
	 * @param inputSet The set to check.
	 */
	public static void useIsInstance(final Set inputSet) {
		final Iterator iter = inputSet.iterator();
		Object obj = null;

		while (iter.hasNext()) {
			obj = iter.next();
			if (Number.class.isInstance(obj)) {
				System.out.println(obj);
			}
		}
	}

	/** 
	 * Demonstration method for class comparison based on passed class and object.
	 *
	 * @param dataType The data type to check.
	 * @param inputSet The input set to check.
	 *
	 * @throws NullPointerException If the data type given is null.
	 */
	public static void useIsInstance2(final Class dataType, final Set inputSet) {
		if (dataType == null) {
			throw new NullPointerException();
		}

		final Iterator iter = inputSet.iterator();
		Object obj = null;

		while (iter.hasNext()) {
			obj = iter.next();
			if (dataType.isInstance(obj)) {
				System.out.println(obj);
			}
		}
	}

	/**
	 * A bad version of useInstance. If you uncomment this method you will get a compiler
	 * error.
	 */

	// public static void useIsInstance3(final Class dataType, final Set inputSet) {
	//   final Iterator iter = inputSet.iterator();
	//   Object obj = null;
	//   while (iter.hasNext()) {
	//     obj = iter.next();
	//     if (obj instanceof dataType) {
	//       System.out.println(obj);
	//     }
	//   }
	// }
}

/* ########## End of File ########## */