com.phoenixst.collections.IdentityPredicate.java Source code

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Here is the source code for com.phoenixst.collections.IdentityPredicate.java

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/*
 *  $Id: IdentityPredicate.java,v 1.7 2005/10/03 15:11:54 rconner Exp $
 *
 *  Copyright (C) 1994-2005 by Phoenix Software Technologists,
 *  Inc. and others.  All rights reserved.
 *
 *  THIS PROGRAM AND DOCUMENTATION IS PROVIDED UNDER THE TERMS OF THE
 *  COMMON PUBLIC LICENSE ("AGREEMENT") WHICH ACCOMPANIES IT.  ANY
 *  USE, REPRODUCTION OR DISTRIBUTION OF THE PROGRAM CONSTITUTES
 *  RECIPIENT'S ACCEPTANCE OF THE AGREEMENT.
 *
 *  The license text can also be found at
 *    http://opensource.org/licenses/cpl.php
 */

package com.phoenixst.collections;

import org.apache.commons.collections.Predicate;

/**
 *  A <code>Predicate</code> which simply tests the {@link #evaluate
 *  evaluate( object )} argument for reference equality with a
 *  specified object.
 *
 *  <P>This is mostly equivalent to the class of the same name in
 *  Jakarta Commons-Collections 3.0, except that it exposes the test
 *  object used in the constructor.  No equivalent exists in version
 *  2.1.
 *
 *  @version    $Revision: 1.7 $
 *  @author     Ray A. Conner
 *
 *  @since      1.0
 */
public final class IdentityPredicate implements Predicate, java.io.Serializable {

    private static final long serialVersionUID = 1L;

    /**
     *  The object to test for equality.
     *
     *  @serial
     */
    private final Object testObject;

    /**
     *  Creates a new <code>IdentityPredicate</code> with the
     *  specified test object.
     */
    public IdentityPredicate(Object testObject) {
        super();
        this.testObject = testObject;
    }

    public boolean evaluate(Object object) {
        return testObject == object;
    }

    /**
     *  Returns the test object being used by this
     *  <code>IdentityPredicate</code>.
     */
    public Object getTestObject() {
        return testObject;
    }

    public boolean equals(Object object) {
        if (object == this) {
            return true;
        }
        if (!(object instanceof IdentityPredicate)) {
            return false;
        }
        return testObject == ((IdentityPredicate) object).testObject;
    }

    public int hashCode() {
        // 17 & 37 are arbitrary, but non-zero and prime
        return 17 * 37 + ((testObject == null) ? 0 : testObject.hashCode());
    }

    public String toString() {
        StringBuilder s = new StringBuilder();
        s.append("Identity(");
        s.append(testObject);
        s.append(")");
        return s.toString();
    }

}