totalpredicate.java

一个关于java 的常用工具包

package org.jutil.predicate;

import java.util.Collection;
import java.util.Iterator;
import java.util.ConcurrentModificationException;

/**
 * <p>A class of Predicates that do not throw exceptions.</p>
 * 
 * <center><img src="doc-files/TotalPredicate.png"/></center>
 *
 * <p>If your predicate don't throw exceptions, you should subclass 
 * TotalPredicate. This saves the client from writing useless try-catch 
 * blocks.</p>
 *
 * <p>Typically, this class will be used as an anonymous inner class as follows:</p>
 * <pre>
 *TotalPredicate myPredicate = new TotalPredicate() {
 *            public boolean eval(Object o) {
 *              //calculate boolean value
 *              //using the given object
 *            }
 *
 *            public int nbSubPredicates() {
 *              // ...
 *            }
 *
 *            public List getSubPredicates() {
 *              // ...
 *            }
 *          };
 * </pre>
 *
 * <p>Note that if your predicate doesn't contain any sub predicates,
 * it should extend <a href="PrimitiveTotalPredicate.html"><code>PrimitiveTotalPredicate</code></a>
 * instead of this class.</p>
 *
 * @path    $Source: /cvsroot/org-jutil/jutil.org/src/org/jutil/predicate/TotalPredicate.java,v $
 * @version $Revision: 1.3 $
 * @date    $Date: 2002/09/07 09:24:11 $
 * @state   $State: Exp $
 * @author  Marko van Dooren
 * @release $Name:  $
 */
public abstract class TotalPredicate extends AbstractPredicate {

  /* The revision of this class */
  public final static String CVS_REVISION ="$Revision: 1.3 $";
    
 /*@
   @ also public behavior
   @
   @ // A total predicate never throws an exception.
   @ signals (Exception) false;
   @*/
  public abstract boolean eval(Object object);

 /*@
	 @ also public behavior
	 @
	 @ post \result == true;
	 @
	 @ public model boolean isValidElement(Object o);
	 @*/

 /*@
   @ also public behavior
	 @
	 @ // No Exception can be thrown
	 @ signals (Exception) false;
	 @*/
  public boolean exists(Collection collection) {
		try {
			return super.exists(collection);
		}
		catch(Exception exc) {
			throw new Error("Exception occurred in org.jutil.predicate.total.TotalPredicate.exists");
		}
  }

 /*@
   @ also public behavior
	 @
	 @ // No Exception can be thrown
	 @ signals (Exception) false;
	 @*/
  public boolean forall(Collection collection) {
		try {
			return super.forall(collection);
		}
		catch(Exception exc) {
			throw new Error("Exception occurred in org.jutil.predicate.total.TotalPredicate.forall");
		}
  }

 /*@
   @ also public behavior
	 @
	 @ // No Exception can be thrown
	 @ signals (Exception) false;
	 @*/
  public int count(Collection collection) {
		try {
			return super.count(collection);
		}
		catch(Exception exc) {
			throw new Error("Exception occurred in org.jutil.predicate.total.TotalPredicate.count");
		}
  }

 /*@
   @ also public behavior
	 @
	 @ // No Exception can be thrown
	 @ signals (Exception) false;
	 @*/
  public void filter(Collection collection) {
		// The backup costs too much, we don't want to do that here.
    if (collection != null) {
      Iterator iter = collection.iterator();
      while (iter.hasNext()) {
        if (! eval(iter.next())) {
          iter.remove();
        }
      }
    }
  }

}
/*
 * <copyright>Copyright (C) 1997-2002. This software is copyrighted by 
 * the people and entities mentioned after the "@author" tags above, on 
 * behalf of the JUTIL.ORG Project. The copyright is dated by the dates 
 * after the "@date" tags above. All rights reserved.
 * This software is published under the terms of the JUTIL.ORG Software
 * License version 1.1 or later, a copy of which has been included with
 * this distribution in the LICENSE file, which can also be found at
 * http://org-jutil.sourceforge.net/LICENSE. This software is distributed 
 * WITHOUT ANY WARRANTY; without even the implied warranty of 
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 
 * See the JUTIL.ORG Software License for more details. For more information,
 * please see http://org-jutil.sourceforge.net/</copyright>
 */