com.phoenixst.collections.AndPredicate.java Source code

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

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/*
 *  $Id: AndPredicate.java,v 1.10 2006/06/07 16:33:30 rconner Exp $
 *
 *  Copyright (C) 1994-2006 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 java.io.*;

import org.apache.commons.collections.Predicate;

/**
 *  A <code>Predicate</code> which returns the logical short-circuit
 *  <em>and</em> of its operands.
 *
 *  <P>This is mostly equivalent to the class of the same name in
 *  Jakarta Commons-Collections 3.0.  This version exposes its
 *  constructor arguments through public accessor methods.  The
 *  deserialization process in this version checks for null fields.
 *  No equivalent exists in version 2.1.
 *
 *  @version    $Revision: 1.10 $
 *  @author     Ray A. Conner
 *
 *  @since      1.0
 */
public final class AndPredicate implements Predicate, Serializable {

    private static final long serialVersionUID = 1L;

    /**
     *  The left operand.
     *
     *  @serial
     */
    private final Predicate left;

    /**
     *  The right operand.
     *
     *  @serial
     */
    private final Predicate right;

    /**
     *  Creates a new <code>AndPredicate</code>.
     */
    public AndPredicate(Predicate left, Predicate right) {
        super();
        this.left = left;
        this.right = right;
        if (left == null) {
            throw new IllegalArgumentException("Left Predicate is null.");
        }
        if (right == null) {
            throw new IllegalArgumentException("Right Predicate is null.");
        }
    }

    private void readObject(ObjectInputStream in) throws ClassNotFoundException, IOException {
        in.defaultReadObject();
        if (left == null) {
            throw new InvalidObjectException("Left Predicate is null.");
        }
        if (right == null) {
            throw new InvalidObjectException("Right Predicate is null.");
        }
    }

    public boolean evaluate(Object object) {
        return left.evaluate(object) && right.evaluate(object);
    }

    /**
     *  Returns the left operand being used by this
     *  <code>AndPredicate</code>.
     */
    public Predicate getLeftOperand() {
        return left;
    }

    /**
     *  Returns the right operand being used by this
     *  <code>AndPredicate</code>.
     */
    public Predicate getRightOperand() {
        return right;
    }

    public boolean equals(Object object) {
        if (object == this) {
            return true;
        }
        if (!(object instanceof AndPredicate)) {
            return false;
        }
        AndPredicate pred = (AndPredicate) object;
        return left.equals(pred.left) && right.equals(pred.right);
    }

    public int hashCode() {
        // 17 & 37 are arbitrary, but non-zero and prime
        int result = 17;
        result = 37 * result + left.hashCode();
        result = 37 * result + right.hashCode();
        return result;
    }

    public String toString() {
        StringBuilder s = new StringBuilder();
        s.append("(");
        s.append(left);
        s.append(" AND ");
        s.append(right);
        s.append(")");
        return s.toString();
    }

}