andfilter.java

一个关于java 的常用工具包

package org.jutil.java.collections;
import java.util.Arrays;


/**
 * <p>The effect of this filter is the same as of a filter with the
 * conjunction of the criteria of the filters it was build with.</p>
 *
 * <center>
 *   <img src="doc-files/AndFilter.png"/>
 * </center>
 *
 * <p>Different filters can be applied to a collection consecutively.
 * It is however more performant if all criteria are applied to the elements
 * of the set at once. The AndFilter does just that. It either retains only the
 * objects satisfying all criteria, or it only discards the objects matching
 * all criteria.</p>
 *
 * <p>You can use <code>TypeFilter</code> like this:</p>
 * <pre><code>
 * new TypeFilter(new Filter[]{filter1, filter2, ...}).retain(collection);
 * </code></pre>
 * 
 * <pre><code>
 * new TypeFilter(myFilters).retain(collection);
 * </code></pre>
 *
 * @path    $Source: /cvsroot/org-jutil/jutil.org/src/org/jutil/java/collections/AndFilter.java,v $
 * @version $Revision: 1.11 $
 * @date    $Date: 2002/07/21 17:56:59 $
 * @state   $State: Exp $
 * @author  Jan Dockx
 * @author  Marko van Dooren 
 * @release $Name:  $
 */
public final class AndFilter extends Filter {

	/* The revision of this class */
	public final static String CVS_REVISION ="$Revision: 1.11 $";

  /**
   * <p>A new Filter that filters objects based on the criteria of all
   * the filters provided in <filters>.</p>
   *
   * @param  filters
   *         The array of filters to be used by this conjuntion filter.
   */
 /*@
	 @ public behavior
	 @
   @ // The given array of filters may not be null.
   @ pre filters != null;
   @ // The given array may only contain effective Filter objects
   @ pre (\forall int i; (i>=0) && (i<filters.length); filters[i] != null);
   @
   @ // The filters of this AndFilter are set to the given filters.
   @ post Arrays.equals(getFilters(),filters);
   @*/
  public AndFilter(Filter[] filters) {
    $filters = (Filter[]) filters.clone();
  }
  
  /**
	 * Return the filters used by this AndFilter.
	 */
 /*@
	 @ public behavior
	 @
	 @ post \result != null;
	 @ post (\forall int i; (i>=0) && (i<\result.length); \result[i] != null);
	 @*/
  public final Filter[] getFilters() {
    return (Filter[]) $filters.clone();
  }
  
	/**
	 * The filters used by this AndFilter.
	 */
 /*@
   @ // $filters must be effective
   @ private invariant $filters != null;
   @ // $filters may only contain effective filters
   @ private invariant (\forall int i; (i>=0) && (i<$filters.length); $filters[i] != null);
   @*/
  private Filter[] $filters;

	/**
	 * See superclass
	 */
 /*@
   @ also public behavior
	 @
   @ post (\forall int i; i>=0 && i<getFilters().length;
	 @        getFilters()[i].criterion(element));
	 @*/
	public final boolean criterion(Object element) {
    boolean result = true;
    // the for loop stops when result == false
    for (int i = 0; result && (i < $filters.length); i++) {
      result = $filters[i].criterion(element);
    }
    return result;
  }

}

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License version 1.1 or later, a copy of which has been included with
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