Mega Code Archive
Null Safe Equals and Hash
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/*
* Copyright 2002-2007 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
//package net.gqu.utils;
import java.lang.reflect.Array;
import java.util.Arrays;
/**
* Miscellaneous object utility methods. Mainly for internal use within the
* framework; consider Jakarta's Commons Lang for a more comprehensive suite
* of object utilities.
*
* @author Juergen Hoeller
* @author Keith Donald
* @author Rod Johnson
* @author Rob Harrop
* @author Alex Ruiz
* @since 19.03.2004
* @see org.apache.commons.lang.ObjectUtils
*/
public abstract class ObjectUtils {
private static final int INITIAL_HASH = 7;
private static final int MULTIPLIER = 31;
/**
* Determine if the given objects are equal, returning <code>true</code>
* if both are <code>null</code> or <code>false</code> if only one is
* <code>null</code>.
* <p>Compares arrays with <code>Arrays.equals</code>, performing an equality
* check based on the array elements rather than the array reference.
* @param o1 first Object to compare
* @param o2 second Object to compare
* @return whether the given objects are equal
* @see java.util.Arrays#equals
*/
public static boolean nullSafeEquals(Object o1, Object o2) {
if (o1 == o2) {
return true;
}
if (o1 == null || o2 == null) {
return false;
}
if (o1.equals(o2)) {
return true;
}
if (o1 instanceof Object[] && o2 instanceof Object[]) {
return Arrays.equals((Object[]) o1, (Object[]) o2);
}
if (o1 instanceof boolean[] && o2 instanceof boolean[]) {
return Arrays.equals((boolean[]) o1, (boolean[]) o2);
}
if (o1 instanceof byte[] && o2 instanceof byte[]) {
return Arrays.equals((byte[]) o1, (byte[]) o2);
}
if (o1 instanceof char[] && o2 instanceof char[]) {
return Arrays.equals((char[]) o1, (char[]) o2);
}
if (o1 instanceof double[] && o2 instanceof double[]) {
return Arrays.equals((double[]) o1, (double[]) o2);
}
if (o1 instanceof float[] && o2 instanceof float[]) {
return Arrays.equals((float[]) o1, (float[]) o2);
}
if (o1 instanceof int[] && o2 instanceof int[]) {
return Arrays.equals((int[]) o1, (int[]) o2);
}
if (o1 instanceof long[] && o2 instanceof long[]) {
return Arrays.equals((long[]) o1, (long[]) o2);
}
if (o1 instanceof short[] && o2 instanceof short[]) {
return Arrays.equals((short[]) o1, (short[]) o2);
}
return false;
}
/**
* Return as hash code for the given object; typically the value of
* <code>{@link Object#hashCode()}</code>. If the object is an array,
* this method will delegate to any of the <code>nullSafeHashCode</code>
* methods for arrays in this class. If the object is <code>null</code>,
* this method returns 0.
* @see #nullSafeHashCode(Object[])
* @see #nullSafeHashCode(boolean[])
* @see #nullSafeHashCode(byte[])
* @see #nullSafeHashCode(char[])
* @see #nullSafeHashCode(double[])
* @see #nullSafeHashCode(float[])
* @see #nullSafeHashCode(int[])
* @see #nullSafeHashCode(long[])
* @see #nullSafeHashCode(short[])
*/
public static int nullSafeHashCode(Object obj) {
if (obj == null) {
return 0;
}
if (obj instanceof Object[]) {
return nullSafeHashCode((Object[]) obj);
}
if (obj instanceof boolean[]) {
return nullSafeHashCode((boolean[]) obj);
}
if (obj instanceof byte[]) {
return nullSafeHashCode((byte[]) obj);
}
if (obj instanceof char[]) {
return nullSafeHashCode((char[]) obj);
}
if (obj instanceof double[]) {
return nullSafeHashCode((double[]) obj);
}
if (obj instanceof float[]) {
return nullSafeHashCode((float[]) obj);
}
if (obj instanceof int[]) {
return nullSafeHashCode((int[]) obj);
}
if (obj instanceof long[]) {
return nullSafeHashCode((long[]) obj);
}
if (obj instanceof short[]) {
return nullSafeHashCode((short[]) obj);
}
return obj.hashCode();
}
/**
* Return a hash code based on the contents of the specified array.
* If <code>array</code> is <code>null</code>, this method returns 0.
*/
public static int nullSafeHashCode(Object[] array) {
if (array == null) {
return 0;
}
int hash = INITIAL_HASH;
int arraySize = array.length;
for (int i = 0; i < arraySize; i++) {
hash = MULTIPLIER * hash + nullSafeHashCode(array[i]);
}
return hash;
}
/**
* Return a hash code based on the contents of the specified array.
* If <code>array</code> is <code>null</code>, this method returns 0.
*/
public static int nullSafeHashCode(boolean[] array) {
if (array == null) {
return 0;
}
int hash = INITIAL_HASH;
int arraySize = array.length;
for (int i = 0; i < arraySize; i++) {
hash = MULTIPLIER * hash + hashCode(array[i]);
}
return hash;
}
/**
* Return a hash code based on the contents of the specified array.
* If <code>array</code> is <code>null</code>, this method returns 0.
*/
public static int nullSafeHashCode(byte[] array) {
if (array == null) {
return 0;
}
int hash = INITIAL_HASH;
int arraySize = array.length;
for (int i = 0; i < arraySize; i++) {
hash = MULTIPLIER * hash + array[i];
}
return hash;
}
/**
* Return a hash code based on the contents of the specified array.
* If <code>array</code> is <code>null</code>, this method returns 0.
*/
public static int nullSafeHashCode(char[] array) {
if (array == null) {
return 0;
}
int hash = INITIAL_HASH;
int arraySize = array.length;
for (int i = 0; i < arraySize; i++) {
hash = MULTIPLIER * hash + array[i];
}
return hash;
}
/**
* Return a hash code based on the contents of the specified array.
* If <code>array</code> is <code>null</code>, this method returns 0.
*/
public static int nullSafeHashCode(double[] array) {
if (array == null) {
return 0;
}
int hash = INITIAL_HASH;
int arraySize = array.length;
for (int i = 0; i < arraySize; i++) {
hash = MULTIPLIER * hash + hashCode(array[i]);
}
return hash;
}
/**
* Return a hash code based on the contents of the specified array.
* If <code>array</code> is <code>null</code>, this method returns 0.
*/
public static int nullSafeHashCode(float[] array) {
if (array == null) {
return 0;
}
int hash = INITIAL_HASH;
int arraySize = array.length;
for (int i = 0; i < arraySize; i++) {
hash = MULTIPLIER * hash + hashCode(array[i]);
}
return hash;
}
/**
* Return a hash code based on the contents of the specified array.
* If <code>array</code> is <code>null</code>, this method returns 0.
*/
public static int nullSafeHashCode(int[] array) {
if (array == null) {
return 0;
}
int hash = INITIAL_HASH;
int arraySize = array.length;
for (int i = 0; i < arraySize; i++) {
hash = MULTIPLIER * hash + array[i];
}
return hash;
}
/**
* Return a hash code based on the contents of the specified array.
* If <code>array</code> is <code>null</code>, this method returns 0.
*/
public static int nullSafeHashCode(long[] array) {
if (array == null) {
return 0;
}
int hash = INITIAL_HASH;
int arraySize = array.length;
for (int i = 0; i < arraySize; i++) {
hash = MULTIPLIER * hash + hashCode(array[i]);
}
return hash;
}
/**
* Return a hash code based on the contents of the specified array.
* If <code>array</code> is <code>null</code>, this method returns 0.
*/
public static int nullSafeHashCode(short[] array) {
if (array == null) {
return 0;
}
int hash = INITIAL_HASH;
int arraySize = array.length;
for (int i = 0; i < arraySize; i++) {
hash = MULTIPLIER * hash + array[i];
}
return hash;
}
/**
* Return the same value as <code>{@link Boolean#hashCode()}</code>.
* @see Boolean#hashCode()
*/
public static int hashCode(boolean bool) {
return bool ? 1231 : 1237;
}
/**
* Return the same value as <code>{@link Double#hashCode()}</code>.
* @see Double#hashCode()
*/
public static int hashCode(double dbl) {
long bits = Double.doubleToLongBits(dbl);
return hashCode(bits);
}
/**
* Return the same value as <code>{@link Float#hashCode()}</code>.
* @see Float#hashCode()
*/
public static int hashCode(float flt) {
return Float.floatToIntBits(flt);
}
/**
* Return the same value as <code>{@link Long#hashCode()}</code>.
* @see Long#hashCode()
*/
public static int hashCode(long lng) {
return (int) (lng ^ (lng >>> 32));
}
}
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