commons-lang-1.0.1.jar - Apache Commons Lang

commons-lang-1.0.1.jar is the JAR file for Apache Commons Lang 1.0.1, which provides a host of helper utilities for the java.lang API.

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File name: commons-lang-1.0.1.jar
File size: 63980 bytes
Date modified: 11/22/2002
Download: Apache Commons Lang Website

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org/apache/commons/lang/builder/EqualsBuilder.java

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2002 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "The Jakarta Project", "Commons", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */
package org.apache.commons.lang.builder;

import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
/**
 * <code>Equals</code> generation routines. 
 * <p>
 * This class provides methods to build a good equals method for any class.  
 * It follows rules laid out in Effective Java, by Joshua Bloch. In particular
 * the rule for comparing <code>doubles </code>, <code>floats</code>, and 
 * arrays can be tricky. Also, making  sure that <code>equals()</code>
 * and <code>hashCode()</code> are consistent can be difficult.
 * <p>
 * Two object that compare as equals must generate the same hash code. But two
 * objects with the same hash code do not have to be equal.
 * <p>
 * All relevant fields should be included in the calculation of equals. Derived
 * fields may be ignored. In particular, any field used in generating a hash 
 * code must be used in the equals method, and vice versa.
 * <p>
 * Typical use for the code is as follows:
 * <pre>
 * public boolean equals(Object o) {
 *   if (!o instanceof MyClass) {
 *    return false;
 *   }
 *  MyClass rhs = (MyClass) o;
 *  return new EqualsBuilder()
 *                 .append(field1, rhs.field1)
 *                 .append(field2, rhs.field2)
 *                 .append(field3, rhs.field3)
 *                 .isEquals();
 *  }
 * </pre>
 * <p>
 * Alternatively, there is a method that uses reflection to determine
 * the fields to test. Because these fields are usually private, the method, 
 * <code>reflectionEquals</code>, uses <code>Field.setAccessible</code> to change
 * the visibility of the fields. This will fail under a security manager, 
 * unless the appropriate permissions are set. It is also slower than testing 
 * explicitly.
 * <p>
 * A typical invocation for this method would look like:
 * <pre>
 * public boolean equals(Object o) {
 *   return EqualsBuilder.reflectionEquals(this, obj);
 * }
 * </pre>
 * 
 * @author <a href="mailto:steve.downey@netfolio.com">Steve Downey</a>
 * @author <a href="mailto:scolebourne@joda.org">Stephen Colebourne</a>
 * @version $Id: EqualsBuilder.java,v 1.4 2002/10/01 20:00:43 stevencaswell Exp $
 */
public class EqualsBuilder {
    /**
     * If the fields tested are equals.
     */
    private boolean isEquals;

    /**
     * Constructor for EqualsBuilder.
     * Starts off assuming that equals is true.
     * @see java.lang.Object#Object()
     */
    public EqualsBuilder() {
        super();
        isEquals = true;
    }

    //-------------------------------------------------------------------------
    
    /**
     * This method uses reflection to determine if the two object are equal. 
     * <p>
     * It uses Field.setAccessible to gain access to private fields. This means
     * that it will throw a security exception if run under a security manger, if
     * the permissions are not set up.
     * It is also not as efficient as testing explicitly. 
     * Transient members will be not be tested, as they are likely derived
     * fields, and not part of the value of the object.
     * Static fields will not be tested.
     * 
     * @param lhs  Left Hand Side
     * @param rhs  Right Hand Side
     * @return boolean - if the two objects have tested equals.
     */
    public static boolean reflectionEquals(Object lhs, Object rhs) {
        return reflectionEquals(lhs, rhs, false);
    }

    /**
     * This method uses reflection to determine if the two object are equal. 
     * <p>
     * It uses Field.setAccessible to gain access to private fields. This means
     * that it will throw a security exception if run under a security manger, if
     * the permissions are not set up.
     * It is also not as efficient as testing explicitly. 
     * If the TestTransients parameter is set to true, transient members will be
     * tested, otherwise they are ignored, as they are likely derived fields, and
     * not part of the value of the object. 
     * Static fields will not be tested.
     * 
     * @param lhs  Left Hand Side
     * @param rhs  Right Hand Side
     * @param testTransients  whether to include transient fields
     * @return boolean - if the two objects have tested equals.
     */
    public static boolean reflectionEquals(Object lhs, Object rhs, 
            boolean testTransients) {
        if (lhs == rhs) {
            return true;
        }
        if (lhs == null || rhs == null) {
            return false;
        }
        Class c1 = lhs.getClass();
        if (!c1.isInstance(rhs)) {
            return false;
        }
        Field[] fields = c1.getDeclaredFields();
        Field.setAccessible(fields, true);
        EqualsBuilder equalsBuilder = new EqualsBuilder();
        for (int i = 0; i < fields.length && equalsBuilder.isEquals; ++i) {
            Field f = fields[i];
            if (testTransients || !Modifier.isTransient(f.getModifiers())) {
                if (!Modifier.isStatic(f.getModifiers())) {
                    try {
                        equalsBuilder.append(f.get(lhs), f.get(rhs));
                    } catch (IllegalAccessException e) {
                        //this can't happen. Would get a Security exception instead
                        //throw a runtime exception in case the impossible happens.
                        throw new InternalError("Unexpected IllegalAccessException");
                    }
                }
            }
        }
        return equalsBuilder.isEquals();
    }

    //-------------------------------------------------------------------------
    
    /**
     * Test if two <code>Object</code>s are equal using their <code>equals</code>
     *  method.
     * @param lhs - Left Hand Side
     * @param rhs - Right Hand Side
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(Object lhs, Object rhs) {
        if (isEquals == false) {
            return this;
        }
        if (lhs == rhs) {
            return this;
        }
        if (lhs == null || rhs == null) {
            isEquals = false;
            return this;
        }
        Class lhsClass = lhs.getClass();
        if (!lhsClass.isArray()) {
            //the simple case, not an array, just test the element 
            isEquals = lhs.equals(rhs);
        } else {
            //'Switch' on type of array, to dispatch to the correct handler
            // This handles multi dimensional arrays
            if (lhs instanceof long[]) {
                append((long[]) lhs, (long[]) rhs);
            } else if (lhs instanceof int[]) {
                append((int[]) lhs, (int[]) rhs);
            } else if (lhs instanceof short[]) {
                append((short[]) lhs, (short[]) rhs);
            } else if (lhs instanceof char[]) {
                append((char[]) lhs, (char[]) rhs);
            } else if (lhs instanceof byte[]) {
                append((byte[]) lhs, (byte[]) rhs);
            } else if (lhs instanceof double[]) {
                append((double[]) lhs, (double[]) rhs);
            } else if (lhs instanceof float[]) {
                append((float[]) lhs, (float[]) rhs);
            } else if (lhs instanceof boolean[]) {
                append((boolean[]) lhs, (boolean[]) rhs);
            } else {
                // Not an array of primitives
                append((Object[]) lhs, (Object[]) rhs);
            }
        }
        return this;
    }

    /**
     * Test if two <code>long</code>s are equal using ==.
     * @param lhs - Left Hand Side
     * @param rhs - Right Hand Side
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(long lhs, long rhs) {
        if (isEquals == false) {
            return this;
        }
        isEquals = (lhs == rhs);
        return this;
    }

    /**
     * Test if two <code>int</code>s are equal using ==.
     * @param lhs - Left Hand Side
     * @param rhs - Right Hand Side
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(int lhs, int rhs) {
        if (isEquals == false) {
            return this;
        }
        isEquals = (lhs == rhs);
        return this;
    }

    /**
     * Test if two <code>short</code>s are equal using ==.
     * @param lhs - Left Hand Side
     * @param rhs - Right Hand Side
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(short lhs, short rhs) {
        if (isEquals == false) {
            return this;
        }
        isEquals = (lhs == rhs);
        return this;
    }

    /**
     * Test if two <code>char</code>s are equal using ==.
     * @param lhs - Left Hand Side
     * @param rhs - Right Hand Side
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(char lhs, char rhs) {
        if (isEquals == false) {
            return this;
        }
        isEquals = (lhs == rhs);
        return this;
    }

    /**
     * Test if two <code>byte</code>s are equal using ==.
     * @param lhs - Left Hand Side
     * @param rhs - Right Hand Side
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(byte lhs, byte rhs) {
        if (isEquals == false) {
            return this;
        }
        isEquals = (lhs == rhs);
        return this;
    }

    /**
     * Test if two <code>double</code>s are equal by testing that the 
     * pattern of bits returned by doubleToLong are equal. This handles NaNs, 
     * Infinties, and -0.0. It is compatible with the hash code generated by 
     * <code>HashCodeBuilder</code>.
     * @param lhs - Left Hand Side
     * @param rhs - Right Hand Side
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(double lhs, double rhs) {
        if (isEquals == false) {
            return this;
        }
        return append(Double.doubleToLongBits(lhs), Double.doubleToLongBits(rhs));
    }

    /**
     * Test if two <code>float</code>s are equal byt testing that the 
     * pattern of bits returned by doubleToLong are equal. This handles NaNs, 
     * Infinties, and -0.0. It is compatible with the hash code generated by 
     * <code>HashCodeBuilder</code>.
     * @param lhs - Left Hand Side
     * @param rhs - Right Hand Side
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(float lhs, float rhs) {
        if (isEquals == false) {
            return this;
        }
        return append(Float.floatToIntBits(lhs), Float.floatToIntBits(rhs));
    }

    /**
     * Test if two <code>booleans</code>s are equal using ==.
     * @param lhs - Left Hand Side
     * @param rhs - Right Hand Side
     * @return EqualsBuilder - used to chain calls.
      */
    public EqualsBuilder append(boolean lhs, boolean rhs) {
        if (isEquals == false) {
            return this;
        }
        isEquals = (lhs == rhs);
        return this;
    }

    /**
     * Performs a deep comparison of two object arrays. This also will be
     * called for the top level of multi-dimensional, ragged, and multi-typed
     * arrays. 
     * @param lhs - Left Hand Side
     * @param rhs - Right Hand Side
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(Object[] lhs, Object[] rhs) {
        if (isEquals == false) {
            return this;
        }
        if (lhs == rhs) {
            return this;
        }
        if (lhs == null || rhs == null) {
            isEquals = false;
            return this;
        }
        if (lhs.length != rhs.length) {
            isEquals = false;
            return this;
        }
        for (int i = 0; i < lhs.length && isEquals; ++i) {
            Class lhsClass = lhs[i].getClass();
            if (!lhsClass.isInstance(rhs[i])) {
                isEquals = false; //If the types don't match, not equal
                break;
            }
            append(lhs[i], rhs[i]);
        }
        return this;
    }

    /**
     * Deep comparison of array of <code>long</code> Length and all values
     *  are compared. The method append(long, long) is used.
     * @param lhs - Left Hand Side
     * @param rhs - Right Hand Side
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(long[] lhs, long[] rhs) {
        if (isEquals == false) {
            return this;
        }
        if (lhs == rhs) {
            return this;
        }
        if (lhs == null || rhs == null) {
            isEquals = false;
            return this;
        }
        if (lhs.length != rhs.length) {
            isEquals = false;
            return this;
        }
        for (int i = 0; i < lhs.length && isEquals; ++i) {
            append(lhs[i], rhs[i]);
        }
        return this;
    }

    /**
     * Deep comparison of array of <code>int</code> Length and all values
     *  are compared. The method append(int, int) is used.
     * @param lhs - Left Hand Side
     * @param rhs - Right Hand Side
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(int[] lhs, int[] rhs) {
        if (isEquals == false) {
            return this;
        }
        if (lhs == rhs) {
            return this;
        }
        if (lhs == null || rhs == null) {
            isEquals = false;
            return this;
        }
        if (lhs.length != rhs.length) {
            isEquals = false;
            return this;
        }
        for (int i = 0; i < lhs.length && isEquals; ++i) {
            append(lhs[i], rhs[i]);
        }
        return this;
    }

    /**
     * Deep comparison of array of <code>short</code> Length and all values
     *  are compared. The method append(short, short) is used.
     * @param lhs - Left Hand Side
     * @param rhs - Right Hand Side
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(short[] lhs, short[] rhs) {
        if (isEquals == false) {
            return this;
        }
        if (lhs == rhs) {
            return this;
        }
        if (lhs == null || rhs == null) {
            isEquals = false;
            return this;
        }
        if (lhs.length != rhs.length) {
            isEquals = false;
            return this;
        }
        for (int i = 0; i < lhs.length && isEquals; ++i) {
            append(lhs[i], rhs[i]);
        }
        return this;
    }

    /**
     * Deep comparison of array of <code>char</code> Length and all values
     *  are compared. The method append(char, char) is used.
     * @param lhs - Left Hand Side
     * @param rhs - Right Hand Side
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(char[] lhs, char[] rhs) {
        if (isEquals == false) {
            return this;
        }
        if (lhs == rhs) {
            return this;
        }
        if (lhs == null || rhs == null) {
            isEquals = false;
            return this;
        }
        if (lhs.length != rhs.length) {
            isEquals = false;
            return this;
        }
        for (int i = 0; i < lhs.length && isEquals; ++i) {
            append(lhs[i], rhs[i]);
        }
        return this;
    }

    /**
     * Deep comparison of array of <code>byte</code> Length and all values
     *  are compared. The method append(byte, byte) is used.
     * @param lhs - Left Hand Side
     * @param rhs - Right Hand Side
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(byte[] lhs, byte[] rhs) {
        if (isEquals == false) {
            return this;
        }
        if (lhs == rhs) {
            return this;
        }
        if (lhs == null || rhs == null) {
            isEquals = false;
            return this;
        }
        if (lhs.length != rhs.length) {
            isEquals = false;
            return this;
        }
        for (int i = 0; i < lhs.length && isEquals; ++i) {
            append(lhs[i], rhs[i]);
        }
        return this;
    }

    /**
     * Deep comparison of array of <code>double</code> Length and all values
     *  are compared. The method append(double, double) is used.
     * @param lhs - Left Hand Side
     * @param rhs - Right Hand Side
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(double[] lhs, double[] rhs) {
        if (isEquals == false) {
            return this;
        }
        if (lhs == rhs) {
            return this;
        }
        if (lhs == null || rhs == null) {
            isEquals = false;
            return this;
        }
        if (lhs.length != rhs.length) {
            isEquals = false;
            return this;
        }
        for (int i = 0; i < lhs.length && isEquals; ++i) {
            append(lhs[i], rhs[i]);
        }
        return this;
    }

    /**
     * Deep comparison of array of <code>float</code> Length and all values
     *  are compared. The method append(float, float) is used.
     * @param lhs - Left Hand Side
     * @param rhs - Right Hand Side
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(float[] lhs, float[] rhs) {
        if (isEquals == false) {
            return this;
        }
        if (lhs == rhs) {
            return this;
        }
        if (lhs == null || rhs == null) {
            isEquals = false;
            return this;
        }
        if (lhs.length != rhs.length) {
            isEquals = false;
            return this;
        }
        for (int i = 0; i < lhs.length && isEquals; ++i) {
            append(lhs[i], rhs[i]);
        }
        return this;
    }

    /**
     * Deep comparison of array of <code>boolean</code> Length and all values
     *  are compared. The method append(boolean, boolean) is used.
     * @param lhs - Left Hand Side
     * @param rhs - Right Hand Side
     * @return EqualsBuilder - used to chain calls.
     */
    public EqualsBuilder append(boolean[] lhs, boolean[] rhs) {
        if (isEquals == false) {
            return this;
        }
        if (lhs == rhs) {
            return this;
        }
        if (lhs == null || rhs == null) {
            isEquals = false;
            return this;
        }
        if (lhs.length != rhs.length) {
            isEquals = false;
            return this;
        }
        for (int i = 0; i < lhs.length && isEquals; ++i) {
            append(lhs[i], rhs[i]);
        }
        return this;
    }

    /**
     * Return true if the fields that have been checked are all equal.
     * @return boolean
     */
    public boolean isEquals() {
        return isEquals;
    }

}

org/apache/commons/lang/builder/EqualsBuilder.java

 

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