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The Spring Framework ObjectUtils.java source code
/*
* 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 org.springframework.util;
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;
private static final String EMPTY_STRING = "";
private static final String NULL_STRING = "null";
private static final String ARRAY_START = "{";
private static final String ARRAY_END = "}";
private static final String EMPTY_ARRAY = ARRAY_START + ARRAY_END;
private static final String ARRAY_ELEMENT_SEPARATOR = ", ";
/**
* Return whether the given throwable is a checked exception:
* that is, neither a RuntimeException nor an Error.
* @param ex the throwable to check
* @return whether the throwable is a checked exception
* @see java.lang.Exception
* @see java.lang.RuntimeException
* @see java.lang.Error
*/
public static boolean isCheckedException(Throwable ex) {
return !(ex instanceof RuntimeException || ex instanceof Error);
}
/**
* Check whether the given exception is compatible with the exceptions
* declared in a throws clause.
* @param ex the exception to checked
* @param declaredExceptions the exceptions declared in the throws clause
* @return whether the given exception is compatible
*/
public static boolean isCompatibleWithThrowsClause(Throwable ex, Class[] declaredExceptions) {
if (!isCheckedException(ex)) {
return true;
}
if (declaredExceptions != null) {
for (int i = 0; i < declaredExceptions.length; i++) {
if (declaredExceptions[i].isAssignableFrom(ex.getClass())) {
return true;
}
}
}
return false;
}
/**
* Return whether the given array is empty: that is, <code>null
* or of zero length.
* @param array the array to check
* @return whether the given array is empty
*/
public static boolean isEmpty(Object[] array) {
return (array == null || array.length == 0);
}
/**
* Check whether the given array contains the given element.
* @param array the array to check (may be <code>null,
* in which case the return value will always be <code>false)
* @param element the element to check for
* @return whether the element has been found in the given array
*/
public static boolean containsElement(Object[] array, Object element) {
if (array == null) {
return false;
}
for (int i = 0; i < array.length; i++) {
if (nullSafeEquals(array[i], element)) {
return true;
}
}
return false;
}
/**
* Append the given Object to the given array, returning a new array
* consisting of the input array contents plus the given Object.
* @param array the array to append to (can be <code>null)
* @param obj the Object to append
* @return the new array (of the same component type; never <code>null)
*/
public static Object[] addObjectToArray(Object[] array, Object obj) {
Class compType = Object.class;
if (array != null) {
compType = array.getClass().getComponentType();
}
else if (obj != null) {
compType = obj.getClass();
}
int newArrLength = (array != null ? array.length + 1 : 1);
Object[] newArr = (Object[]) Array.newInstance(compType, newArrLength);
if (array != null) {
System.arraycopy(array, 0, newArr, 0, array.length);
}
newArr[newArr.length - 1] = obj;
return newArr;
}
/**
* Convert the given array (which may be a primitive array) to an
* object array (if necessary of primitive wrapper objects).
* <p>A null source value will be converted to an
* empty Object array.
* @param source the (potentially primitive) array
* @return the corresponding object array (never <code>null)
* @throws IllegalArgumentException if the parameter is not an array
*/
public static Object[] toObjectArray(Object source) {
if (source instanceof Object[]) {
return (Object[]) source;
}
if (source == null) {
return new Object[0];
}
if (!source.getClass().isArray()) {
throw new IllegalArgumentException("Source is not an array: " + source);
}
int length = Array.getLength(source);
if (length == 0) {
return new Object[0];
}
Class wrapperType = Array.get(source, 0).getClass();
Object[] newArray = (Object[]) Array.newInstance(wrapperType, length);
for (int i = 0; i < length; i++) {
newArray[i] = Array.get(source, i);
}
return newArray;
}
//---------------------------------------------------------------------
// Convenience methods for content-based equality/hash-code handling
//---------------------------------------------------------------------
/**
* Determine if the given objects are equal, returning <code>true
* if both are <code>null or false if only one is
* <code>null.
* <p>Compares arrays with Arrays.equals, 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.getClass().isArray() && o2.getClass().isArray()) {
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()}. If the object is an array,
* this method will delegate to any of the <code>nullSafeHashCode
* methods for arrays in this class. If the object is <code>null,
* 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.getClass().isArray()) {
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 is null, 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 is null, 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 is null, 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 is null, 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 is null, 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 is null, 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 is null, 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 is null, 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 is null, 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()}.
* @see Boolean#hashCode()
*/
public static int hashCode(boolean bool) {
return bool ? 1231 : 1237;
}
/**
* Return the same value as <code>{@link Double#hashCode()}.
* @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()}.
* @see Float#hashCode()
*/
public static int hashCode(float flt) {
return Float.floatToIntBits(flt);
}
/**
* Return the same value as <code>{@link Long#hashCode()}.
* @see Long#hashCode()
*/
public static int hashCode(long lng) {
return (int) (lng ^ (lng >>> 32));
}
//---------------------------------------------------------------------
// Convenience methods for toString output
//---------------------------------------------------------------------
/**
* Return a String representation of an object's overall identity.
* @param obj the object (may be <code>null)
* @return the object's identity as String representation,
* or an empty String if the object was <code>null
*/
public static String identityToString(Object obj) {
if (obj == null) {
return EMPTY_STRING;
}
return obj.getClass().getName() + "@" + getIdentityHexString(obj);
}
/**
* Return a hex String form of an object's identity hash code.
* @param obj the object
* @return the object's identity code in hex notation
*/
public static String getIdentityHexString(Object obj) {
return Integer.toHexString(System.identityHashCode(obj));
}
/**
* Return a content-based String representation if <code>obj is
* not <code>null; otherwise returns an empty String.
* <p>Differs from {@link #nullSafeToString(Object)} in that it returns
* an empty String rather than "null" for a <code>null value.
* @param obj the object to build a display String for
* @return a display String representation of <code>obj
* @see #nullSafeToString(Object)
*/
public static String getDisplayString(Object obj) {
if (obj == null) {
return EMPTY_STRING;
}
return nullSafeToString(obj);
}
/**
* Determine the class name for the given object.
* <p>Returns "null" if obj is null.
* @param obj the object to introspect (may be <code>null)
* @return the corresponding class name
*/
public static String nullSafeClassName(Object obj) {
return (obj != null ? obj.getClass().getName() : NULL_STRING);
}
/**
* Return a String representation of the specified Object.
* <p>Builds a String representation of the contents in case of an array.
* Returns <code>"null" if obj is null.
* @param obj the object to build a String representation for
* @return a String representation of <code>obj
*/
public static String nullSafeToString(Object obj) {
if (obj == null) {
return NULL_STRING;
}
if (obj instanceof String) {
return (String) obj;
}
if (obj instanceof Object[]) {
return nullSafeToString((Object[]) obj);
}
if (obj instanceof boolean[]) {
return nullSafeToString((boolean[]) obj);
}
if (obj instanceof byte[]) {
return nullSafeToString((byte[]) obj);
}
if (obj instanceof char[]) {
return nullSafeToString((char[]) obj);
}
if (obj instanceof double[]) {
return nullSafeToString((double[]) obj);
}
if (obj instanceof float[]) {
return nullSafeToString((float[]) obj);
}
if (obj instanceof int[]) {
return nullSafeToString((int[]) obj);
}
if (obj instanceof long[]) {
return nullSafeToString((long[]) obj);
}
if (obj instanceof short[]) {
return nullSafeToString((short[]) obj);
}
String str = obj.toString();
return (str != null ? str : EMPTY_STRING);
}
/**
* Return a String representation of the contents of the specified array.
* <p>The String representation consists of a list of the array's elements,
* enclosed in curly braces (<code>"{}"). Adjacent elements are separated
* by the characters <code>", " (a comma followed by a space). Returns
* <code>"null" if array is null.
* @param array the array to build a String representation for
* @return a String representation of <code>array
*/
public static String nullSafeToString(Object[] array) {
if (array == null) {
return NULL_STRING;
}
int length = array.length;
if (length == 0) {
return EMPTY_ARRAY;
}
StringBuffer buffer = new StringBuffer();
for (int i = 0; i < length; i++) {
if (i == 0) {
buffer.append(ARRAY_START);
}
else {
buffer.append(ARRAY_ELEMENT_SEPARATOR);
}
buffer.append(String.valueOf(array[i]));
}
buffer.append(ARRAY_END);
return buffer.toString();
}
/**
* Return a String representation of the contents of the specified array.
* <p>The String representation consists of a list of the array's elements,
* enclosed in curly braces (<code>"{}"). Adjacent elements are separated
* by the characters <code>", " (a comma followed by a space). Returns
* <code>"null" if array is null.
* @param array the array to build a String representation for
* @return a String representation of <code>array
*/
public static String nullSafeToString(boolean[] array) {
if (array == null) {
return NULL_STRING;
}
int length = array.length;
if (length == 0) {
return EMPTY_ARRAY;
}
StringBuffer buffer = new StringBuffer();
for (int i = 0; i < length; i++) {
if (i == 0) {
buffer.append(ARRAY_START);
}
else {
buffer.append(ARRAY_ELEMENT_SEPARATOR);
}
buffer.append(array[i]);
}
buffer.append(ARRAY_END);
return buffer.toString();
}
/**
* Return a String representation of the contents of the specified array.
* <p>The String representation consists of a list of the array's elements,
* enclosed in curly braces (<code>"{}"). Adjacent elements are separated
* by the characters <code>", " (a comma followed by a space). Returns
* <code>"null" if array is null.
* @param array the array to build a String representation for
* @return a String representation of <code>array
*/
public static String nullSafeToString(byte[] array) {
if (array == null) {
return NULL_STRING;
}
int length = array.length;
if (length == 0) {
return EMPTY_ARRAY;
}
StringBuffer buffer = new StringBuffer();
for (int i = 0; i < length; i++) {
if (i == 0) {
buffer.append(ARRAY_START);
}
else {
buffer.append(ARRAY_ELEMENT_SEPARATOR);
}
buffer.append(array[i]);
}
buffer.append(ARRAY_END);
return buffer.toString();
}
/**
* Return a String representation of the contents of the specified array.
* <p>The String representation consists of a list of the array's elements,
* enclosed in curly braces (<code>"{}"). Adjacent elements are separated
* by the characters <code>", " (a comma followed by a space). Returns
* <code>"null" if array is null.
* @param array the array to build a String representation for
* @return a String representation of <code>array
*/
public static String nullSafeToString(char[] array) {
if (array == null) {
return NULL_STRING;
}
int length = array.length;
if (length == 0) {
return EMPTY_ARRAY;
}
StringBuffer buffer = new StringBuffer();
for (int i = 0; i < length; i++) {
if (i == 0) {
buffer.append(ARRAY_START);
}
else {
buffer.append(ARRAY_ELEMENT_SEPARATOR);
}
buffer.append("'").append(array[i]).append("'");
}
buffer.append(ARRAY_END);
return buffer.toString();
}
/**
* Return a String representation of the contents of the specified array.
* <p>The String representation consists of a list of the array's elements,
* enclosed in curly braces (<code>"{}"). Adjacent elements are separated
* by the characters <code>", " (a comma followed by a space). Returns
* <code>"null" if array is null.
* @param array the array to build a String representation for
* @return a String representation of <code>array
*/
public static String nullSafeToString(double[] array) {
if (array == null) {
return NULL_STRING;
}
int length = array.length;
if (length == 0) {
return EMPTY_ARRAY;
}
StringBuffer buffer = new StringBuffer();
for (int i = 0; i < length; i++) {
if (i == 0) {
buffer.append(ARRAY_START);
}
else {
buffer.append(ARRAY_ELEMENT_SEPARATOR);
}
buffer.append(array[i]);
}
buffer.append(ARRAY_END);
return buffer.toString();
}
/**
* Return a String representation of the contents of the specified array.
* <p>The String representation consists of a list of the array's elements,
* enclosed in curly braces (<code>"{}"). Adjacent elements are separated
* by the characters <code>", " (a comma followed by a space). Returns
* <code>"null" if array is null.
* @param array the array to build a String representation for
* @return a String representation of <code>array
*/
public static String nullSafeToString(float[] array) {
if (array == null) {
return NULL_STRING;
}
int length = array.length;
if (length == 0) {
return EMPTY_ARRAY;
}
StringBuffer buffer = new StringBuffer();
for (int i = 0; i < length; i++) {
if (i == 0) {
buffer.append(ARRAY_START);
}
else {
buffer.append(ARRAY_ELEMENT_SEPARATOR);
}
buffer.append(array[i]);
}
buffer.append(ARRAY_END);
return buffer.toString();
}
/**
* Return a String representation of the contents of the specified array.
* <p>The String representation consists of a list of the array's elements,
* enclosed in curly braces (<code>"{}"). Adjacent elements are separated
* by the characters <code>", " (a comma followed by a space). Returns
* <code>"null" if array is null.
* @param array the array to build a String representation for
* @return a String representation of <code>array
*/
public static String nullSafeToString(int[] array) {
if (array == null) {
return NULL_STRING;
}
int length = array.length;
if (length == 0) {
return EMPTY_ARRAY;
}
StringBuffer buffer = new StringBuffer();
for (int i = 0; i < length; i++) {
if (i == 0) {
buffer.append(ARRAY_START);
}
else {
buffer.append(ARRAY_ELEMENT_SEPARATOR);
}
buffer.append(array[i]);
}
buffer.append(ARRAY_END);
return buffer.toString();
}
/**
* Return a String representation of the contents of the specified array.
* <p>The String representation consists of a list of the array's elements,
* enclosed in curly braces (<code>"{}"). Adjacent elements are separated
* by the characters <code>", " (a comma followed by a space). Returns
* <code>"null" if array is null.
* @param array the array to build a String representation for
* @return a String representation of <code>array
*/
public static String nullSafeToString(long[] array) {
if (array == null) {
return NULL_STRING;
}
int length = array.length;
if (length == 0) {
return EMPTY_ARRAY;
}
StringBuffer buffer = new StringBuffer();
for (int i = 0; i < length; i++) {
if (i == 0) {
buffer.append(ARRAY_START);
}
else {
buffer.append(ARRAY_ELEMENT_SEPARATOR);
}
buffer.append(array[i]);
}
buffer.append(ARRAY_END);
return buffer.toString();
}
/**
* Return a String representation of the contents of the specified array.
* <p>The String representation consists of a list of the array's elements,
* enclosed in curly braces (<code>"{}"). Adjacent elements are separated
* by the characters <code>", " (a comma followed by a space). Returns
* <code>"null" if array is null.
* @param array the array to build a String representation for
* @return a String representation of <code>array
*/
public static String nullSafeToString(short[] array) {
if (array == null) {
return NULL_STRING;
}
int length = array.length;
if (length == 0) {
return EMPTY_ARRAY;
}
StringBuffer buffer = new StringBuffer();
for (int i = 0; i < length; i++) {
if (i == 0) {
buffer.append(ARRAY_START);
}
else {
buffer.append(ARRAY_ELEMENT_SEPARATOR);
}
buffer.append(array[i]);
}
buffer.append(ARRAY_END);
return buffer.toString();
}
}
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