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From scolebou...@apache.org
Subject cvs commit: jakarta-commons/lang/src/java/org/apache/commons/lang/builder EqualsBuilder.java
Date Thu, 12 Sep 2002 22:00:00 GMT
scolebourne    2002/09/12 15:00:00

  Added:       lang/src/java/org/apache/commons/lang/builder
                        EqualsBuilder.java
  Log:
  Added code from Steve Downey, 
  with some formatting changes and minor bug fixes
  
  Revision  Changes    Path
  1.1                  jakarta-commons/lang/src/java/org/apache/commons/lang/builder/EqualsBuilder.java
  
  Index: 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:
   * <code>
   * public boolean equals(Object o) {
   *   if (!o instanceof MyClass) {
   *    return false;
   *   }
   *  MyClass rhs = (MyClass) o;
   *  return new EqualsBuilder()
   *                 .test(field1, rhs.field1)
   *                 .test(field2, rhs.field2)
   *                 .test(field3, rhs.field3)
   *                 .isEquals();
   *  }
   * </code>
   * <p>
   * Alternatively, there is a method that uses reflection to determine
   * the fields to test. Because these fields are usually private, the method, 
   * <code>reflectionTest</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:
   * <code>
   * public boolean equals(Object o) {
   *   return EqualsBuilder.reflectionEquals(this, obj);
   * }
   * </code>
   * 
   * @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 1.1 2002/09/12 22:00:00 scolebourne Exp $
   */
  public class EqualsBuilder {
      /**
       * If the fields tested are equals.
       */
      protected 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. 
       * 
       * @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. 
       * 
       * @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())) {
                  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;
      }
  
  }
  
  
  

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