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/*
* Copyright 2002-2017 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;
import org.springframework.lang.Nullable;
/**
* Miscellaneous object utility methods.
*
*
* Mainly for internal use within the framework.
*
*
* Thanks to Alex Ruiz for contributing several enhancements to this class!
*
* @author Juergen Hoeller
* @author Keith Donald
* @author Rod Johnson
* @author Rob Harrop
* @author Chris Beams
* @author Sam Brannen
* @since 19.03.2004
* @see ClassUtils
* @see CollectionUtils
* @see StringUtils
*/
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 = ", ";
/**
* Determine whether the given array is empty: i.e. {@code null} or of zero length.
*
* @param array the array to check
* @see #isEmpty(Object)
*/
public static boolean isEmpty(@Nullable Object[] array) {
return (array == null || array.length == 0);
}
/**
* Convert the given array (which may be a primitive array) to an object array (if necessary of
* primitive wrapper objects).
*
* A {@code 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(@Nullable 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
* {@code false} if only one is {@code null}.
*
* Compares arrays with {@code 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 Object#equals(Object)
* @see java.util.Arrays#equals
*/
public static boolean nullSafeEquals(@Nullable Object o1, @Nullable 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()) {
return arrayEquals(o1, o2);
}
return false;
}
/**
* Compare the given arrays with {@code Arrays.equals}, performing an equality check based on the
* array elements rather than the array reference.
*
* @param o1 first array to compare
* @param o2 second array to compare
* @return whether the given objects are equal
* @see #nullSafeEquals(Object, Object)
* @see java.util.Arrays#equals
*/
private static boolean arrayEquals(Object o1, Object o2) {
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 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 Object#hashCode()
* @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(@Nullable 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
* {@code null}, this method returns 0.
*/
public static int nullSafeHashCode(@Nullable Object[] array) {
if (array == null) {
return 0;
}
int hash = INITIAL_HASH;
for (Object element : array) {
hash = MULTIPLIER * hash + nullSafeHashCode(element);
}
return hash;
}
/**
* Return a hash code based on the contents of the specified array. If {@code array} is
* {@code null}, this method returns 0.
*/
public static int nullSafeHashCode(@Nullable boolean[] array) {
if (array == null) {
return 0;
}
int hash = INITIAL_HASH;
for (boolean element : array) {
hash = MULTIPLIER * hash + Boolean.hashCode(element);
}
return hash;
}
/**
* Return a hash code based on the contents of the specified array. If {@code array} is
* {@code null}, this method returns 0.
*/
public static int nullSafeHashCode(@Nullable byte[] array) {
if (array == null) {
return 0;
}
int hash = INITIAL_HASH;
for (byte element : array) {
hash = MULTIPLIER * hash + element;
}
return hash;
}
/**
* Return a hash code based on the contents of the specified array. If {@code array} is
* {@code null}, this method returns 0.
*/
public static int nullSafeHashCode(@Nullable char[] array) {
if (array == null) {
return 0;
}
int hash = INITIAL_HASH;
for (char element : array) {
hash = MULTIPLIER * hash + element;
}
return hash;
}
/**
* Return a hash code based on the contents of the specified array. If {@code array} is
* {@code null}, this method returns 0.
*/
public static int nullSafeHashCode(@Nullable double[] array) {
if (array == null) {
return 0;
}
int hash = INITIAL_HASH;
for (double element : array) {
hash = MULTIPLIER * hash + Double.hashCode(element);
}
return hash;
}
/**
* Return a hash code based on the contents of the specified array. If {@code array} is
* {@code null}, this method returns 0.
*/
public static int nullSafeHashCode(@Nullable float[] array) {
if (array == null) {
return 0;
}
int hash = INITIAL_HASH;
for (float element : array) {
hash = MULTIPLIER * hash + Float.hashCode(element);
}
return hash;
}
/**
* Return a hash code based on the contents of the specified array. If {@code array} is
* {@code null}, this method returns 0.
*/
public static int nullSafeHashCode(@Nullable int[] array) {
if (array == null) {
return 0;
}
int hash = INITIAL_HASH;
for (int element : array) {
hash = MULTIPLIER * hash + element;
}
return hash;
}
/**
* Return a hash code based on the contents of the specified array. If {@code array} is
* {@code null}, this method returns 0.
*/
public static int nullSafeHashCode(@Nullable long[] array) {
if (array == null) {
return 0;
}
int hash = INITIAL_HASH;
for (long element : array) {
hash = MULTIPLIER * hash + Long.hashCode(element);
}
return hash;
}
/**
* Return a hash code based on the contents of the specified array. If {@code array} is
* {@code null}, this method returns 0.
*/
public static int nullSafeHashCode(@Nullable short[] array) {
if (array == null) {
return 0;
}
int hash = INITIAL_HASH;
for (short element : array) {
hash = MULTIPLIER * hash + element;
}
return hash;
}
// ---------------------------------------------------------------------
// Convenience methods for toString output
// ---------------------------------------------------------------------
/**
* Return a String representation of the specified Object.
*
* Builds a String representation of the contents in case of an array. Returns {@code "null"} if
* {@code obj} is {@code null}.
*
* @param obj the object to build a String representation for
* @return a String representation of {@code obj}
*/
public static String nullSafeToString(@Nullable 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.
*
* 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 {@code array} is {@code null}.
*
* @param array the array to build a String representation for
* @return a String representation of {@code array}
*/
public static String nullSafeToString(@Nullable Object[] array) {
if (array == null) {
return NULL_STRING;
}
int length = array.length;
if (length == 0) {
return EMPTY_ARRAY;
}
StringBuilder sb = new StringBuilder();
for (int i = 0; i < length; i++) {
if (i == 0) {
sb.append(ARRAY_START);
} else {
sb.append(ARRAY_ELEMENT_SEPARATOR);
}
sb.append(String.valueOf(array[i]));
}
sb.append(ARRAY_END);
return sb.toString();
}
/**
* Return a String representation of the contents of the specified array.
*
* 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 {@code array} is {@code null}.
*
* @param array the array to build a String representation for
* @return a String representation of {@code array}
*/
public static String nullSafeToString(@Nullable boolean[] array) {
if (array == null) {
return NULL_STRING;
}
int length = array.length;
if (length == 0) {
return EMPTY_ARRAY;
}
StringBuilder sb = new StringBuilder();
for (int i = 0; i < length; i++) {
if (i == 0) {
sb.append(ARRAY_START);
} else {
sb.append(ARRAY_ELEMENT_SEPARATOR);
}
sb.append(array[i]);
}
sb.append(ARRAY_END);
return sb.toString();
}
/**
* Return a String representation of the contents of the specified array.
*
* 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 {@code array} is {@code null}.
*
* @param array the array to build a String representation for
* @return a String representation of {@code array}
*/
public static String nullSafeToString(@Nullable byte[] array) {
if (array == null) {
return NULL_STRING;
}
int length = array.length;
if (length == 0) {
return EMPTY_ARRAY;
}
StringBuilder sb = new StringBuilder();
for (int i = 0; i < length; i++) {
if (i == 0) {
sb.append(ARRAY_START);
} else {
sb.append(ARRAY_ELEMENT_SEPARATOR);
}
sb.append(array[i]);
}
sb.append(ARRAY_END);
return sb.toString();
}
/**
* Return a String representation of the contents of the specified array.
*
* 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 {@code array} is {@code null}.
*
* @param array the array to build a String representation for
* @return a String representation of {@code array}
*/
public static String nullSafeToString(@Nullable char[] array) {
if (array == null) {
return NULL_STRING;
}
int length = array.length;
if (length == 0) {
return EMPTY_ARRAY;
}
StringBuilder sb = new StringBuilder();
for (int i = 0; i < length; i++) {
if (i == 0) {
sb.append(ARRAY_START);
} else {
sb.append(ARRAY_ELEMENT_SEPARATOR);
}
sb.append("'").append(array[i]).append("'");
}
sb.append(ARRAY_END);
return sb.toString();
}
/**
* Return a String representation of the contents of the specified array.
*
* 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 {@code array} is {@code null}.
*
* @param array the array to build a String representation for
* @return a String representation of {@code array}
*/
public static String nullSafeToString(@Nullable double[] array) {
if (array == null) {
return NULL_STRING;
}
int length = array.length;
if (length == 0) {
return EMPTY_ARRAY;
}
StringBuilder sb = new StringBuilder();
for (int i = 0; i < length; i++) {
if (i == 0) {
sb.append(ARRAY_START);
} else {
sb.append(ARRAY_ELEMENT_SEPARATOR);
}
sb.append(array[i]);
}
sb.append(ARRAY_END);
return sb.toString();
}
/**
* Return a String representation of the contents of the specified array.
*
* 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 {@code array} is {@code null}.
*
* @param array the array to build a String representation for
* @return a String representation of {@code array}
*/
public static String nullSafeToString(@Nullable float[] array) {
if (array == null) {
return NULL_STRING;
}
int length = array.length;
if (length == 0) {
return EMPTY_ARRAY;
}
StringBuilder sb = new StringBuilder();
for (int i = 0; i < length; i++) {
if (i == 0) {
sb.append(ARRAY_START);
} else {
sb.append(ARRAY_ELEMENT_SEPARATOR);
}
sb.append(array[i]);
}
sb.append(ARRAY_END);
return sb.toString();
}
/**
* Return a String representation of the contents of the specified array.
*
* 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 {@code array} is {@code null}.
*
* @param array the array to build a String representation for
* @return a String representation of {@code array}
*/
public static String nullSafeToString(@Nullable int[] array) {
if (array == null) {
return NULL_STRING;
}
int length = array.length;
if (length == 0) {
return EMPTY_ARRAY;
}
StringBuilder sb = new StringBuilder();
for (int i = 0; i < length; i++) {
if (i == 0) {
sb.append(ARRAY_START);
} else {
sb.append(ARRAY_ELEMENT_SEPARATOR);
}
sb.append(array[i]);
}
sb.append(ARRAY_END);
return sb.toString();
}
/**
* Return a String representation of the contents of the specified array.
*
* 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 {@code array} is {@code null}.
*
* @param array the array to build a String representation for
* @return a String representation of {@code array}
*/
public static String nullSafeToString(@Nullable long[] array) {
if (array == null) {
return NULL_STRING;
}
int length = array.length;
if (length == 0) {
return EMPTY_ARRAY;
}
StringBuilder sb = new StringBuilder();
for (int i = 0; i < length; i++) {
if (i == 0) {
sb.append(ARRAY_START);
} else {
sb.append(ARRAY_ELEMENT_SEPARATOR);
}
sb.append(array[i]);
}
sb.append(ARRAY_END);
return sb.toString();
}
/**
* Return a String representation of the contents of the specified array.
*
* 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 {@code array} is {@code null}.
*
* @param array the array to build a String representation for
* @return a String representation of {@code array}
*/
public static String nullSafeToString(@Nullable short[] array) {
if (array == null) {
return NULL_STRING;
}
int length = array.length;
if (length == 0) {
return EMPTY_ARRAY;
}
StringBuilder sb = new StringBuilder();
for (int i = 0; i < length; i++) {
if (i == 0) {
sb.append(ARRAY_START);
} else {
sb.append(ARRAY_ELEMENT_SEPARATOR);
}
sb.append(array[i]);
}
sb.append(ARRAY_END);
return sb.toString();
}
}