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/* * Copyright 2002-2019 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 * * https://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 java.util.Collection; import java.util.Map; import java.util.Optional; import java.util.StringJoiner; import org.springframework.lang.Nullable; /** * Miscellaneous object utility methods. * * <p>Mainly for internal use within the framework. * * <p>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 = ", "; private static final Object[] EMPTY_OBJECT_ARRAY = new Object[0]; /** * 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 specified * exception types, as declared in a throws clause. * @param ex the exception to check * @param declaredExceptions the exception types declared in the throws clause * @return whether the given exception is compatible */ public static boolean isCompatibleWithThrowsClause(Throwable ex, @Nullable Class<?>... declaredExceptions) { if (!isCheckedException(ex)) { return true; } if (declaredExceptions != null) { for (Class<?> declaredException : declaredExceptions) { if (declaredException.isInstance(ex)) { return true; } } } return false; } /** * Determine whether the given object is an array: * either an Object array or a primitive array. * @param obj the object to check */ public static boolean isArray(@Nullable Object obj) { return (obj != null && obj.getClass().isArray()); } /** * 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); } /** * Determine whether the given object is empty. * <p>This method supports the following object types. * <ul> * <li>{@code Optional}: considered empty if {@link Optional#empty()}</li> * <li>{@code Array}: considered empty if its length is zero</li> * <li>{@link CharSequence}: considered empty if its length is zero</li> * <li>{@link Collection}: delegates to {@link Collection#isEmpty()}</li> * <li>{@link Map}: delegates to {@link Map#isEmpty()}</li> * </ul> * <p>If the given object is non-null and not one of the aforementioned * supported types, this method returns {@code false}. * @param obj the object to check * @return {@code true} if the object is {@code null} or <em>empty</em> * @since 4.2 * @see Optional#isPresent() * @see ObjectUtils#isEmpty(Object[]) * @see StringUtils#hasLength(CharSequence) * @see StringUtils#isEmpty(Object) * @see CollectionUtils#isEmpty(java.util.Collection) * @see CollectionUtils#isEmpty(java.util.Map) */ @SuppressWarnings("rawtypes") public static boolean isEmpty(@Nullable Object obj) { if (obj == null) { return true; } if (obj instanceof Optional) { return !((Optional) obj).isPresent(); } if (obj instanceof CharSequence) { return ((CharSequence) obj).length() == 0; } if (obj.getClass().isArray()) { return Array.getLength(obj) == 0; } if (obj instanceof Collection) { return ((Collection) obj).isEmpty(); } if (obj instanceof Map) { return ((Map) obj).isEmpty(); } // else return false; } /** * Unwrap the given object which is potentially a {@link java.util.Optional}. * @param obj the candidate object * @return either the value held within the {@code Optional}, {@code null} * if the {@code Optional} is empty, or simply the given object as-is * @since 5.0 */ @Nullable public static Object unwrapOptional(@Nullable Object obj) { if (obj instanceof Optional) { Optional<?> optional = (Optional<?>) obj; if (!optional.isPresent()) { return null; } Object result = optional.get(); Assert.isTrue(!(result instanceof Optional), "Multi-level Optional usage not supported"); return result; } return obj; } /** * 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(@Nullable Object[] array, Object element) { if (array == null) { return false; } for (Object arrayEle : array) { if (nullSafeEquals(arrayEle, element)) { return true; } } return false; } /** * Check whether the given array of enum constants contains a constant with the given name, * ignoring case when determining a match. * @param enumValues the enum values to check, typically obtained via {@code MyEnum.values()} * @param constant the constant name to find (must not be null or empty string) * @return whether the constant has been found in the given array */ public static boolean containsConstant(Enum<?>[] enumValues, String constant) { return containsConstant(enumValues, constant, false); } /** * Check whether the given array of enum constants contains a constant with the given name. * @param enumValues the enum values to check, typically obtained via {@code MyEnum.values()} * @param constant the constant name to find (must not be null or empty string) * @param caseSensitive whether case is significant in determining a match * @return whether the constant has been found in the given array */ public static boolean containsConstant(Enum<?>[] enumValues, String constant, boolean caseSensitive) { for (Enum<?> candidate : enumValues) { if (caseSensitive ? candidate.toString().equals(constant) : candidate.toString().equalsIgnoreCase(constant)) { return true; } } return false; } /** * Case insensitive alternative to {@link Enum#valueOf(Class, String)}. * @param <E> the concrete Enum type * @param enumValues the array of all Enum constants in question, usually per {@code Enum.values()} * @param constant the constant to get the enum value of * @throws IllegalArgumentException if the given constant is not found in the given array * of enum values. Use {@link #containsConstant(Enum[], String)} as a guard to avoid this exception. */ public static <E extends Enum<?>> E caseInsensitiveValueOf(E[] enumValues, String constant) { for (E candidate : enumValues) { if (candidate.toString().equalsIgnoreCase(constant)) { return candidate; } } throw new IllegalArgumentException("Constant [" + constant + "] does not exist in enum type " + enumValues.getClass().getComponentType().getName()); } /** * 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 <A, O extends A> A[] addObjectToArray(@Nullable A[] array, @Nullable O 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); @SuppressWarnings("unchecked") A[] newArr = (A[]) 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 {@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 EMPTY_OBJECT_ARRAY; } if (!source.getClass().isArray()) { throw new IllegalArgumentException("Source is not an array: " + source); } int length = Array.getLength(source); if (length == 0) { return EMPTY_OBJECT_ARRAY; } 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}. * <p>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; } /** * Return the same value as {@link Boolean#hashCode(boolean)}}. * @deprecated as of Spring Framework 5.0, in favor of the native JDK 8 variant */ @Deprecated public static int hashCode(boolean bool) { return Boolean.hashCode(bool); } /** * Return the same value as {@link Double#hashCode(double)}}. * @deprecated as of Spring Framework 5.0, in favor of the native JDK 8 variant */ @Deprecated public static int hashCode(double dbl) { return Double.hashCode(dbl); } /** * Return the same value as {@link Float#hashCode(float)}}. * @deprecated as of Spring Framework 5.0, in favor of the native JDK 8 variant */ @Deprecated public static int hashCode(float flt) { return Float.hashCode(flt); } /** * Return the same value as {@link Long#hashCode(long)}}. * @deprecated as of Spring Framework 5.0, in favor of the native JDK 8 variant */ @Deprecated public static int hashCode(long lng) { return Long.hashCode(lng); } //--------------------------------------------------------------------- // 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(@Nullable 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(@Nullable Object obj) { if (obj == null) { return EMPTY_STRING; } return nullSafeToString(obj); } /** * Determine the class name for the given object. * <p>Returns a {@code "null"} String if {@code obj} is {@code null}. * @param obj the object to introspect (may be {@code null}) * @return the corresponding class name */ public static String nullSafeClassName(@Nullable 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 a {@code "null"} String 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. * <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 a {@code "null"} String 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; } StringJoiner stringJoiner = new StringJoiner(ARRAY_ELEMENT_SEPARATOR, ARRAY_START, ARRAY_END); for (Object o : array) { stringJoiner.add(String.valueOf(o)); } return stringJoiner.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 a {@code "null"} String 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; } StringJoiner stringJoiner = new StringJoiner(ARRAY_ELEMENT_SEPARATOR, ARRAY_START, ARRAY_END); for (boolean b : array) { stringJoiner.add(String.valueOf(b)); } return stringJoiner.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 a {@code "null"} String 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; } StringJoiner stringJoiner = new StringJoiner(ARRAY_ELEMENT_SEPARATOR, ARRAY_START, ARRAY_END); for (byte b : array) { stringJoiner.add(String.valueOf(b)); } return stringJoiner.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 a {@code "null"} String 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; } StringJoiner stringJoiner = new StringJoiner(ARRAY_ELEMENT_SEPARATOR, ARRAY_START, ARRAY_END); for (char c : array) { stringJoiner.add('\'' + String.valueOf(c) + '\''); } return stringJoiner.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 a {@code "null"} String 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; } StringJoiner stringJoiner = new StringJoiner(ARRAY_ELEMENT_SEPARATOR, ARRAY_START, ARRAY_END); for (double d : array) { stringJoiner.add(String.valueOf(d)); } return stringJoiner.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 a {@code "null"} String 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; } StringJoiner stringJoiner = new StringJoiner(ARRAY_ELEMENT_SEPARATOR, ARRAY_START, ARRAY_END); for (float f : array) { stringJoiner.add(String.valueOf(f)); } return stringJoiner.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 a {@code "null"} String 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; } StringJoiner stringJoiner = new StringJoiner(ARRAY_ELEMENT_SEPARATOR, ARRAY_START, ARRAY_END); for (int i : array) { stringJoiner.add(String.valueOf(i)); } return stringJoiner.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 a {@code "null"} String 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; } StringJoiner stringJoiner = new StringJoiner(ARRAY_ELEMENT_SEPARATOR, ARRAY_START, ARRAY_END); for (long l : array) { stringJoiner.add(String.valueOf(l)); } return stringJoiner.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 a {@code "null"} String 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; } StringJoiner stringJoiner = new StringJoiner(ARRAY_ELEMENT_SEPARATOR, ARRAY_START, ARRAY_END); for (short s : array) { stringJoiner.add(String.valueOf(s)); } return stringJoiner.toString(); } }