| /* | 
 |  * Licensed to the Apache Software Foundation (ASF) under one or more | 
 |  * contributor license agreements.  See the NOTICE file distributed with | 
 |  * this work for additional information regarding copyright ownership. | 
 |  * The ASF licenses this file to You 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.apache.commons.lang3; | 
 |  | 
 | import java.io.IOException; | 
 | import java.io.Serializable; | 
 | import java.lang.reflect.Array; | 
 | import java.lang.reflect.InvocationTargetException; | 
 | import java.lang.reflect.Method; | 
 | import java.time.Duration; | 
 | import java.util.ArrayList; | 
 | import java.util.Collection; | 
 | import java.util.Collections; | 
 | import java.util.Comparator; | 
 | import java.util.HashMap; | 
 | import java.util.Hashtable; | 
 | import java.util.Map; | 
 | import java.util.Objects; | 
 | import java.util.TreeSet; | 
 | import java.util.function.Supplier; | 
 |  | 
 | import org.apache.commons.lang3.exception.CloneFailedException; | 
 | import org.apache.commons.lang3.function.Suppliers; | 
 | import org.apache.commons.lang3.mutable.MutableInt; | 
 | import org.apache.commons.lang3.text.StrBuilder; | 
 | import org.apache.commons.lang3.time.DurationUtils; | 
 |  | 
 | /** | 
 |  * <p>Operations on {@link Object}.</p> | 
 |  * | 
 |  * <p>This class tries to handle {@code null} input gracefully. | 
 |  * An exception will generally not be thrown for a {@code null} input. | 
 |  * Each method documents its behavior in more detail.</p> | 
 |  * | 
 |  * <p>#ThreadSafe#</p> | 
 |  * @since 1.0 | 
 |  */ | 
 | //@Immutable | 
 | @SuppressWarnings("deprecation") // deprecated class StrBuilder is imported | 
 | // because it is part of the signature of deprecated methods | 
 | public class ObjectUtils { | 
 |  | 
 |     /** | 
 |      * <p>Class used as a null placeholder where {@code null} | 
 |      * has another meaning.</p> | 
 |      * | 
 |      * <p>For example, in a {@link HashMap} the | 
 |      * {@link java.util.HashMap#get(java.lang.Object)} method returns | 
 |      * {@code null} if the {@link Map} contains {@code null} or if there is | 
 |      * no matching key. The {@code null} placeholder can be used to distinguish | 
 |      * between these two cases.</p> | 
 |      * | 
 |      * <p>Another example is {@link Hashtable}, where {@code null} | 
 |      * cannot be stored.</p> | 
 |      */ | 
 |     public static class Null implements Serializable { | 
 |         /** | 
 |          * Required for serialization support. Declare serialization compatibility with Commons Lang 1.0 | 
 |          * | 
 |          * @see java.io.Serializable | 
 |          */ | 
 |         private static final long serialVersionUID = 7092611880189329093L; | 
 |  | 
 |         /** | 
 |          * Restricted constructor - singleton. | 
 |          */ | 
 |         Null() { | 
 |         } | 
 |  | 
 |         /** | 
 |          * <p>Ensure singleton.</p> | 
 |          * | 
 |          * @return the singleton value | 
 |          */ | 
 |         private Object readResolve() { | 
 |             return NULL; | 
 |         } | 
 |     } | 
 |  | 
 |     private static final char AT_SIGN = '@'; | 
 |  | 
 |     /** | 
 |      * <p>Singleton used as a {@code null} placeholder where | 
 |      * {@code null} has another meaning.</p> | 
 |      * | 
 |      * <p>For example, in a {@link HashMap} the | 
 |      * {@link java.util.HashMap#get(java.lang.Object)} method returns | 
 |      * {@code null} if the {@link Map} contains {@code null} or if there | 
 |      * is no matching key. The {@code null} placeholder can be used to | 
 |      * distinguish between these two cases.</p> | 
 |      * | 
 |      * <p>Another example is {@link Hashtable}, where {@code null} | 
 |      * cannot be stored.</p> | 
 |      * | 
 |      * <p>This instance is Serializable.</p> | 
 |      */ | 
 |     public static final Null NULL = new Null(); | 
 |  | 
 |     /** | 
 |      * Checks if all values in the array are not {@code nulls}. | 
 |      * | 
 |      * <p> | 
 |      * If any value is {@code null} or the array is {@code null} then | 
 |      * {@code false} is returned. If all elements in array are not | 
 |      * {@code null} or the array is empty (contains no elements) {@code true} | 
 |      * is returned. | 
 |      * </p> | 
 |      * | 
 |      * <pre> | 
 |      * ObjectUtils.allNotNull(*)             = true | 
 |      * ObjectUtils.allNotNull(*, *)          = true | 
 |      * ObjectUtils.allNotNull(null)          = false | 
 |      * ObjectUtils.allNotNull(null, null)    = false | 
 |      * ObjectUtils.allNotNull(null, *)       = false | 
 |      * ObjectUtils.allNotNull(*, null)       = false | 
 |      * ObjectUtils.allNotNull(*, *, null, *) = false | 
 |      * </pre> | 
 |      * | 
 |      * @param values  the values to test, may be {@code null} or empty | 
 |      * @return {@code false} if there is at least one {@code null} value in the array or the array is {@code null}, | 
 |      * {@code true} if all values in the array are not {@code null}s or array contains no elements. | 
 |      * @since 3.5 | 
 |      */ | 
 |     public static boolean allNotNull(final Object... values) { | 
 |         if (values == null) { | 
 |             return false; | 
 |         } | 
 |  | 
 |         for (final Object val : values) { | 
 |             if (val == null) { | 
 |                 return false; | 
 |             } | 
 |         } | 
 |  | 
 |         return true; | 
 |     } | 
 |  | 
 |     /** | 
 |      * Checks if all values in the given array are {@code null}. | 
 |      * | 
 |      * <p> | 
 |      * If all the values are {@code null} or the array is {@code null} | 
 |      * or empty, then {@code true} is returned, otherwise {@code false} is returned. | 
 |      * </p> | 
 |      * | 
 |      * <pre> | 
 |      * ObjectUtils.allNull(*)                = false | 
 |      * ObjectUtils.allNull(*, null)          = false | 
 |      * ObjectUtils.allNull(null, *)          = false | 
 |      * ObjectUtils.allNull(null, null, *, *) = false | 
 |      * ObjectUtils.allNull(null)             = true | 
 |      * ObjectUtils.allNull(null, null)       = true | 
 |      * </pre> | 
 |      * | 
 |      * @param values  the values to test, may be {@code null} or empty | 
 |      * @return {@code true} if all values in the array are {@code null}s, | 
 |      * {@code false} if there is at least one non-null value in the array. | 
 |      * @since 3.11 | 
 |      */ | 
 |     public static boolean allNull(final Object... values) { | 
 |         return !anyNotNull(values); | 
 |     } | 
 |  | 
 |     /** | 
 |      * Checks if any value in the given array is not {@code null}. | 
 |      * | 
 |      * <p> | 
 |      * If all the values are {@code null} or the array is {@code null} | 
 |      * or empty then {@code false} is returned. Otherwise {@code true} is returned. | 
 |      * </p> | 
 |      * | 
 |      * <pre> | 
 |      * ObjectUtils.anyNotNull(*)                = true | 
 |      * ObjectUtils.anyNotNull(*, null)          = true | 
 |      * ObjectUtils.anyNotNull(null, *)          = true | 
 |      * ObjectUtils.anyNotNull(null, null, *, *) = true | 
 |      * ObjectUtils.anyNotNull(null)             = false | 
 |      * ObjectUtils.anyNotNull(null, null)       = false | 
 |      * </pre> | 
 |      * | 
 |      * @param values  the values to test, may be {@code null} or empty | 
 |      * @return {@code true} if there is at least one non-null value in the array, | 
 |      * {@code false} if all values in the array are {@code null}s. | 
 |      * If the array is {@code null} or empty {@code false} is also returned. | 
 |      * @since 3.5 | 
 |      */ | 
 |     public static boolean anyNotNull(final Object... values) { | 
 |         return firstNonNull(values) != null; | 
 |     } | 
 |  | 
 |     /** | 
 |      * Checks if any value in the given array is {@code null}. | 
 |      * | 
 |      * <p> | 
 |      * If any of the values are {@code null} or the array is {@code null}, | 
 |      * then {@code true} is returned, otherwise {@code false} is returned. | 
 |      * </p> | 
 |      * | 
 |      * <pre> | 
 |      * ObjectUtils.anyNull(*)             = false | 
 |      * ObjectUtils.anyNull(*, *)          = false | 
 |      * ObjectUtils.anyNull(null)          = true | 
 |      * ObjectUtils.anyNull(null, null)    = true | 
 |      * ObjectUtils.anyNull(null, *)       = true | 
 |      * ObjectUtils.anyNull(*, null)       = true | 
 |      * ObjectUtils.anyNull(*, *, null, *) = true | 
 |      * </pre> | 
 |      * | 
 |      * @param values  the values to test, may be {@code null} or empty | 
 |      * @return {@code true} if there is at least one {@code null} value in the array, | 
 |      * {@code false} if all the values are non-null. | 
 |      * If the array is {@code null} or empty, {@code true} is also returned. | 
 |      * @since 3.11 | 
 |      */ | 
 |     public static boolean anyNull(final Object... values) { | 
 |         return !allNotNull(values); | 
 |     } | 
 |  | 
 |     /** | 
 |      * <p>Clone an object.</p> | 
 |      * | 
 |      * @param <T> the type of the object | 
 |      * @param obj  the object to clone, null returns null | 
 |      * @return the clone if the object implements {@link Cloneable} otherwise {@code null} | 
 |      * @throws CloneFailedException if the object is cloneable and the clone operation fails | 
 |      * @since 3.0 | 
 |      */ | 
 |     public static <T> T clone(final T obj) { | 
 |         if (obj instanceof Cloneable) { | 
 |             final Object result; | 
 |             if (isArray(obj)) { | 
 |                 final Class<?> componentType = obj.getClass().getComponentType(); | 
 |                 if (componentType.isPrimitive()) { | 
 |                     int length = Array.getLength(obj); | 
 |                     result = Array.newInstance(componentType, length); | 
 |                     while (length-- > 0) { | 
 |                         Array.set(result, length, Array.get(obj, length)); | 
 |                     } | 
 |                 } else { | 
 |                     result = ((Object[]) obj).clone(); | 
 |                 } | 
 |             } else { | 
 |                 try { | 
 |                     final Method clone = obj.getClass().getMethod("clone"); | 
 |                     result = clone.invoke(obj); | 
 |                 } catch (final NoSuchMethodException e) { | 
 |                     throw new CloneFailedException("Cloneable type " | 
 |                         + obj.getClass().getName() | 
 |                         + " has no clone method", e); | 
 |                 } catch (final IllegalAccessException e) { | 
 |                     throw new CloneFailedException("Cannot clone Cloneable type " | 
 |                         + obj.getClass().getName(), e); | 
 |                 } catch (final InvocationTargetException e) { | 
 |                     throw new CloneFailedException("Exception cloning Cloneable type " | 
 |                         + obj.getClass().getName(), e.getCause()); | 
 |                 } | 
 |             } | 
 |             @SuppressWarnings("unchecked") // OK because input is of type T | 
 |             final T checked = (T) result; | 
 |             return checked; | 
 |         } | 
 |  | 
 |         return null; | 
 |     } | 
 |  | 
 |     /** | 
 |      * <p>Clone an object if possible.</p> | 
 |      * | 
 |      * <p>This method is similar to {@link #clone(Object)}, but will return the provided | 
 |      * instance as the return value instead of {@code null} if the instance | 
 |      * is not cloneable. This is more convenient if the caller uses different | 
 |      * implementations (e.g. of a service) and some of the implementations do not allow concurrent | 
 |      * processing or have state. In such cases the implementation can simply provide a proper | 
 |      * clone implementation and the caller's code does not have to change.</p> | 
 |      * | 
 |      * @param <T> the type of the object | 
 |      * @param obj  the object to clone, null returns null | 
 |      * @return the clone if the object implements {@link Cloneable} otherwise the object itself | 
 |      * @throws CloneFailedException if the object is cloneable and the clone operation fails | 
 |      * @since 3.0 | 
 |      */ | 
 |     public static <T> T cloneIfPossible(final T obj) { | 
 |         final T clone = clone(obj); | 
 |         return clone == null ? obj : clone; | 
 |     } | 
 |  | 
 |     /** | 
 |      * <p>Null safe comparison of Comparables. | 
 |      * {@code null} is assumed to be less than a non-{@code null} value.</p> | 
 |      * <p>TODO Move to ComparableUtils.</p> | 
 |      * | 
 |      * @param <T> type of the values processed by this method | 
 |      * @param c1  the first comparable, may be null | 
 |      * @param c2  the second comparable, may be null | 
 |      * @return a negative value if c1 < c2, zero if c1 = c2 | 
 |      *  and a positive value if c1 > c2 | 
 |      */ | 
 |     public static <T extends Comparable<? super T>> int compare(final T c1, final T c2) { | 
 |         return compare(c1, c2, false); | 
 |     } | 
 |  | 
 |     /** | 
 |      * <p>Null safe comparison of Comparables.</p> | 
 |      * <p>TODO Move to ComparableUtils.</p> | 
 |      * | 
 |      * @param <T> type of the values processed by this method | 
 |      * @param c1  the first comparable, may be null | 
 |      * @param c2  the second comparable, may be null | 
 |      * @param nullGreater if true {@code null} is considered greater | 
 |      *  than a non-{@code null} value or if false {@code null} is | 
 |      *  considered less than a Non-{@code null} value | 
 |      * @return a negative value if c1 < c2, zero if c1 = c2 | 
 |      *  and a positive value if c1 > c2 | 
 |      * @see java.util.Comparator#compare(Object, Object) | 
 |      */ | 
 |     public static <T extends Comparable<? super T>> int compare(final T c1, final T c2, final boolean nullGreater) { | 
 |         if (c1 == c2) { | 
 |             return 0; | 
 |         } | 
 |         if (c1 == null) { | 
 |             return nullGreater ? 1 : -1; | 
 |         } | 
 |         if (c2 == null) { | 
 |             return nullGreater ? -1 : 1; | 
 |         } | 
 |         return c1.compareTo(c2); | 
 |     } | 
 |  | 
 |     /** | 
 |      * This method returns the provided value unchanged. | 
 |      * This can prevent javac from inlining a constant | 
 |      * field, e.g., | 
 |      * | 
 |      * <pre> | 
 |      *     public final static boolean MAGIC_FLAG = ObjectUtils.CONST(true); | 
 |      * </pre> | 
 |      * | 
 |      * This way any jars that refer to this field do not | 
 |      * have to recompile themselves if the field's value | 
 |      * changes at some future date. | 
 |      * | 
 |      * @param v the boolean value to return | 
 |      * @return the boolean v, unchanged | 
 |      * @since 3.2 | 
 |      */ | 
 |     public static boolean CONST(final boolean v) { | 
 |         return v; | 
 |     } | 
 |  | 
 |     /** | 
 |      * This method returns the provided value unchanged. | 
 |      * This can prevent javac from inlining a constant | 
 |      * field, e.g., | 
 |      * | 
 |      * <pre> | 
 |      *     public final static byte MAGIC_BYTE = ObjectUtils.CONST((byte) 127); | 
 |      * </pre> | 
 |      * | 
 |      * This way any jars that refer to this field do not | 
 |      * have to recompile themselves if the field's value | 
 |      * changes at some future date. | 
 |      * | 
 |      * @param v the byte value to return | 
 |      * @return the byte v, unchanged | 
 |      * @since 3.2 | 
 |      */ | 
 |     public static byte CONST(final byte v) { | 
 |         return v; | 
 |     } | 
 |  | 
 |     /** | 
 |      * This method returns the provided value unchanged. | 
 |      * This can prevent javac from inlining a constant | 
 |      * field, e.g., | 
 |      * | 
 |      * <pre> | 
 |      *     public final static char MAGIC_CHAR = ObjectUtils.CONST('a'); | 
 |      * </pre> | 
 |      * | 
 |      * This way any jars that refer to this field do not | 
 |      * have to recompile themselves if the field's value | 
 |      * changes at some future date. | 
 |      * | 
 |      * @param v the char value to return | 
 |      * @return the char v, unchanged | 
 |      * @since 3.2 | 
 |      */ | 
 |     public static char CONST(final char v) { | 
 |         return v; | 
 |     } | 
 |  | 
 |     /** | 
 |      * This method returns the provided value unchanged. | 
 |      * This can prevent javac from inlining a constant | 
 |      * field, e.g., | 
 |      * | 
 |      * <pre> | 
 |      *     public final static double MAGIC_DOUBLE = ObjectUtils.CONST(1.0); | 
 |      * </pre> | 
 |      * | 
 |      * This way any jars that refer to this field do not | 
 |      * have to recompile themselves if the field's value | 
 |      * changes at some future date. | 
 |      * | 
 |      * @param v the double value to return | 
 |      * @return the double v, unchanged | 
 |      * @since 3.2 | 
 |      */ | 
 |     public static double CONST(final double v) { | 
 |         return v; | 
 |     } | 
 |  | 
 |     /** | 
 |      * This method returns the provided value unchanged. | 
 |      * This can prevent javac from inlining a constant | 
 |      * field, e.g., | 
 |      * | 
 |      * <pre> | 
 |      *     public final static float MAGIC_FLOAT = ObjectUtils.CONST(1.0f); | 
 |      * </pre> | 
 |      * | 
 |      * This way any jars that refer to this field do not | 
 |      * have to recompile themselves if the field's value | 
 |      * changes at some future date. | 
 |      * | 
 |      * @param v the float value to return | 
 |      * @return the float v, unchanged | 
 |      * @since 3.2 | 
 |      */ | 
 |     public static float CONST(final float v) { | 
 |         return v; | 
 |     } | 
 |  | 
 |     /** | 
 |      * This method returns the provided value unchanged. | 
 |      * This can prevent javac from inlining a constant | 
 |      * field, e.g., | 
 |      * | 
 |      * <pre> | 
 |      *     public final static int MAGIC_INT = ObjectUtils.CONST(123); | 
 |      * </pre> | 
 |      * | 
 |      * This way any jars that refer to this field do not | 
 |      * have to recompile themselves if the field's value | 
 |      * changes at some future date. | 
 |      * | 
 |      * @param v the int value to return | 
 |      * @return the int v, unchanged | 
 |      * @since 3.2 | 
 |      */ | 
 |     public static int CONST(final int v) { | 
 |         return v; | 
 |     } | 
 |  | 
 |     /** | 
 |      * This method returns the provided value unchanged. | 
 |      * This can prevent javac from inlining a constant | 
 |      * field, e.g., | 
 |      * | 
 |      * <pre> | 
 |      *     public final static long MAGIC_LONG = ObjectUtils.CONST(123L); | 
 |      * </pre> | 
 |      * | 
 |      * This way any jars that refer to this field do not | 
 |      * have to recompile themselves if the field's value | 
 |      * changes at some future date. | 
 |      * | 
 |      * @param v the long value to return | 
 |      * @return the long v, unchanged | 
 |      * @since 3.2 | 
 |      */ | 
 |     public static long CONST(final long v) { | 
 |         return v; | 
 |     } | 
 |  | 
 |     /** | 
 |      * This method returns the provided value unchanged. | 
 |      * This can prevent javac from inlining a constant | 
 |      * field, e.g., | 
 |      * | 
 |      * <pre> | 
 |      *     public final static short MAGIC_SHORT = ObjectUtils.CONST((short) 123); | 
 |      * </pre> | 
 |      * | 
 |      * This way any jars that refer to this field do not | 
 |      * have to recompile themselves if the field's value | 
 |      * changes at some future date. | 
 |      * | 
 |      * @param v the short value to return | 
 |      * @return the short v, unchanged | 
 |      * @since 3.2 | 
 |      */ | 
 |     public static short CONST(final short v) { | 
 |         return v; | 
 |     } | 
 |  | 
 |     /** | 
 |      * This method returns the provided value unchanged. | 
 |      * This can prevent javac from inlining a constant | 
 |      * field, e.g., | 
 |      * | 
 |      * <pre> | 
 |      *     public final static String MAGIC_STRING = ObjectUtils.CONST("abc"); | 
 |      * </pre> | 
 |      * | 
 |      * This way any jars that refer to this field do not | 
 |      * have to recompile themselves if the field's value | 
 |      * changes at some future date. | 
 |      * | 
 |      * @param <T> the Object type | 
 |      * @param v the genericized Object value to return (typically a String). | 
 |      * @return the genericized Object v, unchanged (typically a String). | 
 |      * @since 3.2 | 
 |      */ | 
 |     public static <T> T CONST(final T v) { | 
 |         return v; | 
 |     } | 
 |  | 
 |     /** | 
 |      * This method returns the provided value unchanged. | 
 |      * This can prevent javac from inlining a constant | 
 |      * field, e.g., | 
 |      * | 
 |      * <pre> | 
 |      *     public final static byte MAGIC_BYTE = ObjectUtils.CONST_BYTE(127); | 
 |      * </pre> | 
 |      * | 
 |      * This way any jars that refer to this field do not | 
 |      * have to recompile themselves if the field's value | 
 |      * changes at some future date. | 
 |      * | 
 |      * @param v the byte literal (as an int) value to return | 
 |      * @throws IllegalArgumentException if the value passed to v | 
 |      *         is larger than a byte, that is, smaller than -128 or | 
 |      *         larger than 127. | 
 |      * @return the byte v, unchanged | 
 |      * @since 3.2 | 
 |      */ | 
 |     public static byte CONST_BYTE(final int v) { | 
 |         if (v < Byte.MIN_VALUE || v > Byte.MAX_VALUE) { | 
 |             throw new IllegalArgumentException("Supplied value must be a valid byte literal between -128 and 127: [" + v + "]"); | 
 |         } | 
 |         return (byte) v; | 
 |     } | 
 |  | 
 |     /** | 
 |      * This method returns the provided value unchanged. | 
 |      * This can prevent javac from inlining a constant | 
 |      * field, e.g., | 
 |      * | 
 |      * <pre> | 
 |      *     public final static short MAGIC_SHORT = ObjectUtils.CONST_SHORT(127); | 
 |      * </pre> | 
 |      * | 
 |      * This way any jars that refer to this field do not | 
 |      * have to recompile themselves if the field's value | 
 |      * changes at some future date. | 
 |      * | 
 |      * @param v the short literal (as an int) value to return | 
 |      * @throws IllegalArgumentException if the value passed to v | 
 |      *         is larger than a short, that is, smaller than -32768 or | 
 |      *         larger than 32767. | 
 |      * @return the byte v, unchanged | 
 |      * @since 3.2 | 
 |      */ | 
 |     public static short CONST_SHORT(final int v) { | 
 |         if (v < Short.MIN_VALUE || v > Short.MAX_VALUE) { | 
 |             throw new IllegalArgumentException("Supplied value must be a valid byte literal between -32768 and 32767: [" + v + "]"); | 
 |         } | 
 |         return (short) v; | 
 |     } | 
 |  | 
 |     /** | 
 |      * <p>Returns a default value if the object passed is {@code null}.</p> | 
 |      * | 
 |      * <pre> | 
 |      * ObjectUtils.defaultIfNull(null, null)      = null | 
 |      * ObjectUtils.defaultIfNull(null, "")        = "" | 
 |      * ObjectUtils.defaultIfNull(null, "zz")      = "zz" | 
 |      * ObjectUtils.defaultIfNull("abc", *)        = "abc" | 
 |      * ObjectUtils.defaultIfNull(Boolean.TRUE, *) = Boolean.TRUE | 
 |      * </pre> | 
 |      * | 
 |      * @param <T> the type of the object | 
 |      * @param object  the {@link Object} to test, may be {@code null} | 
 |      * @param defaultValue  the default value to return, may be {@code null} | 
 |      * @return {@code object} if it is not {@code null}, defaultValue otherwise | 
 |      * TODO Rename to getIfNull in 4.0 | 
 |      */ | 
 |     public static <T> T defaultIfNull(final T object, final T defaultValue) { | 
 |         return object != null ? object : defaultValue; | 
 |     } | 
 |  | 
 |     // Null-safe equals/hashCode | 
 |     /** | 
 |      * <p>Compares two objects for equality, where either one or both | 
 |      * objects may be {@code null}.</p> | 
 |      * | 
 |      * <pre> | 
 |      * ObjectUtils.equals(null, null)                  = true | 
 |      * ObjectUtils.equals(null, "")                    = false | 
 |      * ObjectUtils.equals("", null)                    = false | 
 |      * ObjectUtils.equals("", "")                      = true | 
 |      * ObjectUtils.equals(Boolean.TRUE, null)          = false | 
 |      * ObjectUtils.equals(Boolean.TRUE, "true")        = false | 
 |      * ObjectUtils.equals(Boolean.TRUE, Boolean.TRUE)  = true | 
 |      * ObjectUtils.equals(Boolean.TRUE, Boolean.FALSE) = false | 
 |      * </pre> | 
 |      * | 
 |      * @param object1  the first object, may be {@code null} | 
 |      * @param object2  the second object, may be {@code null} | 
 |      * @return {@code true} if the values of both objects are the same | 
 |      * @deprecated this method has been replaced by {@code java.util.Objects.equals(Object, Object)} in Java 7 and will | 
 |      * be removed from future releases. | 
 |      */ | 
 |     @Deprecated | 
 |     public static boolean equals(final Object object1, final Object object2) { | 
 |         return Objects.equals(object1, object2); | 
 |     } | 
 |  | 
 |     /** | 
 |      * <p>Returns the first value in the array which is not {@code null}. | 
 |      * If all the values are {@code null} or the array is {@code null} | 
 |      * or empty then {@code null} is returned.</p> | 
 |      * | 
 |      * <pre> | 
 |      * ObjectUtils.firstNonNull(null, null)      = null | 
 |      * ObjectUtils.firstNonNull(null, "")        = "" | 
 |      * ObjectUtils.firstNonNull(null, null, "")  = "" | 
 |      * ObjectUtils.firstNonNull(null, "zz")      = "zz" | 
 |      * ObjectUtils.firstNonNull("abc", *)        = "abc" | 
 |      * ObjectUtils.firstNonNull(null, "xyz", *)  = "xyz" | 
 |      * ObjectUtils.firstNonNull(Boolean.TRUE, *) = Boolean.TRUE | 
 |      * ObjectUtils.firstNonNull()                = null | 
 |      * </pre> | 
 |      * | 
 |      * @param <T> the component type of the array | 
 |      * @param values  the values to test, may be {@code null} or empty | 
 |      * @return the first value from {@code values} which is not {@code null}, | 
 |      *  or {@code null} if there are no non-null values | 
 |      * @since 3.0 | 
 |      */ | 
 |     @SafeVarargs | 
 |     public static <T> T firstNonNull(final T... values) { | 
 |         if (values != null) { | 
 |             for (final T val : values) { | 
 |                 if (val != null) { | 
 |                     return val; | 
 |                 } | 
 |             } | 
 |         } | 
 |         return null; | 
 |     } | 
 |  | 
 |     /** | 
 |      * Delegates to {@link Object#getClass()} using generics. | 
 |      * | 
 |      * @param <T> The argument type or null. | 
 |      * @param object The argument. | 
 |      * @return The argument Class or null. | 
 |      * @since 3.13.0 | 
 |      */ | 
 |     @SuppressWarnings("unchecked") | 
 |     public static <T> Class<T> getClass(final T object) { | 
 |         return object == null ? null : (Class<T>) object.getClass(); | 
 |     } | 
 |  | 
 |     /** | 
 |      * <p>Executes the given suppliers in order and returns the first return | 
 |      * value where a value other than {@code null} is returned. | 
 |      * Once a non-{@code null} value is obtained, all following suppliers are | 
 |      * not executed anymore. | 
 |      * If all the return values are {@code null} or no suppliers are provided | 
 |      * then {@code null} is returned.</p> | 
 |      * | 
 |      * <pre> | 
 |      * ObjectUtils.firstNonNullLazy(null, () -> null) = null | 
 |      * ObjectUtils.firstNonNullLazy(() -> null, () -> "") = "" | 
 |      * ObjectUtils.firstNonNullLazy(() -> "", () -> throw new IllegalStateException()) = "" | 
 |      * ObjectUtils.firstNonNullLazy(() -> null, () -> "zz) = "zz" | 
 |      * ObjectUtils.firstNonNullLazy() = null | 
 |      * </pre> | 
 |      * | 
 |      * @param <T> the type of the return values | 
 |      * @param suppliers  the suppliers returning the values to test. | 
 |      *                   {@code null} values are ignored. | 
 |      *                   Suppliers may return {@code null} or a value of type @{code T} | 
 |      * @return the first return value from {@code suppliers} which is not {@code null}, | 
 |      *  or {@code null} if there are no non-null values | 
 |      * @since 3.10 | 
 |      */ | 
 |     @SafeVarargs | 
 |     public static <T> T getFirstNonNull(final Supplier<T>... suppliers) { | 
 |         if (suppliers != null) { | 
 |             for (final Supplier<T> supplier : suppliers) { | 
 |                 if (supplier != null) { | 
 |                     final T value = supplier.get(); | 
 |                     if (value != null) { | 
 |                         return value; | 
 |                     } | 
 |                 } | 
 |             } | 
 |         } | 
 |         return null; | 
 |     } | 
 |  | 
 |     /** | 
 |      * <p> | 
 |      * Returns the given {@code object} is it is non-null, otherwise returns the Supplier's {@link Supplier#get()} | 
 |      * value. | 
 |      * </p> | 
 |      * | 
 |      * <p> | 
 |      * The caller responsible for thread-safety and exception handling of default value supplier. | 
 |      * </p> | 
 |      * | 
 |      * <pre> | 
 |      * ObjectUtils.getIfNull(null, () -> null)     = null | 
 |      * ObjectUtils.getIfNull(null, null)              = null | 
 |      * ObjectUtils.getIfNull(null, () -> "")       = "" | 
 |      * ObjectUtils.getIfNull(null, () -> "zz")     = "zz" | 
 |      * ObjectUtils.getIfNull("abc", *)                = "abc" | 
 |      * ObjectUtils.getIfNull(Boolean.TRUE, *)         = Boolean.TRUE | 
 |      * </pre> | 
 |      * | 
 |      * @param <T> the type of the object | 
 |      * @param object the {@link Object} to test, may be {@code null} | 
 |      * @param defaultSupplier the default value to return, may be {@code null} | 
 |      * @return {@code object} if it is not {@code null}, {@code defaultValueSupplier.get()} otherwise | 
 |      * @since 3.10 | 
 |      */ | 
 |     public static <T> T getIfNull(final T object, final Supplier<T> defaultSupplier) { | 
 |         return object != null ? object : Suppliers.get(defaultSupplier); | 
 |     } | 
 |  | 
 |     /** | 
 |      * <p>Gets the hash code of an object returning zero when the | 
 |      * object is {@code null}.</p> | 
 |      * | 
 |      * <pre> | 
 |      * ObjectUtils.hashCode(null)   = 0 | 
 |      * ObjectUtils.hashCode(obj)    = obj.hashCode() | 
 |      * </pre> | 
 |      * | 
 |      * @param obj  the object to obtain the hash code of, may be {@code null} | 
 |      * @return the hash code of the object, or zero if null | 
 |      * @since 2.1 | 
 |      * @deprecated this method has been replaced by {@code java.util.Objects.hashCode(Object)} in Java 7 and will be | 
 |      * removed in future releases | 
 |      */ | 
 |     @Deprecated | 
 |     public static int hashCode(final Object obj) { | 
 |         // hashCode(Object) for performance vs. hashCodeMulti(Object[]), as hash code is often critical | 
 |         return Objects.hashCode(obj); | 
 |     } | 
 |  | 
 |     /** | 
 |      * Returns the hex hash code for the given object per {@link Objects#hashCode(Object)}. | 
 |      * <p> | 
 |      * Short hand for {@code Integer.toHexString(Objects.hashCode(object))}. | 
 |      * </p> | 
 |      * | 
 |      * @param object object for which the hashCode is to be calculated | 
 |      * @return Hash code in hexadecimal format. | 
 |      * @since 3.13.0 | 
 |      */ | 
 |     public static String hashCodeHex(final Object object) { | 
 |         return Integer.toHexString(Objects.hashCode(object)); | 
 |     } | 
 |  | 
 |  | 
 |     /** | 
 |      * <p>Gets the hash code for multiple objects.</p> | 
 |      * | 
 |      * <p>This allows a hash code to be rapidly calculated for a number of objects. | 
 |      * The hash code for a single object is the <em>not</em> same as {@link #hashCode(Object)}. | 
 |      * The hash code for multiple objects is the same as that calculated by an | 
 |      * {@link ArrayList} containing the specified objects.</p> | 
 |      * | 
 |      * <pre> | 
 |      * ObjectUtils.hashCodeMulti()                 = 1 | 
 |      * ObjectUtils.hashCodeMulti((Object[]) null)  = 1 | 
 |      * ObjectUtils.hashCodeMulti(a)                = 31 + a.hashCode() | 
 |      * ObjectUtils.hashCodeMulti(a,b)              = (31 + a.hashCode()) * 31 + b.hashCode() | 
 |      * ObjectUtils.hashCodeMulti(a,b,c)            = ((31 + a.hashCode()) * 31 + b.hashCode()) * 31 + c.hashCode() | 
 |      * </pre> | 
 |      * | 
 |      * @param objects  the objects to obtain the hash code of, may be {@code null} | 
 |      * @return the hash code of the objects, or zero if null | 
 |      * @since 3.0 | 
 |      * @deprecated this method has been replaced by {@code java.util.Objects.hash(Object...)} in Java 7 and will be | 
 |      * removed in future releases. | 
 |      */ | 
 |     @Deprecated | 
 |     public static int hashCodeMulti(final Object... objects) { | 
 |         int hash = 1; | 
 |         if (objects != null) { | 
 |             for (final Object object : objects) { | 
 |                 final int tmpHash = Objects.hashCode(object); | 
 |                 hash = hash * 31 + tmpHash; | 
 |             } | 
 |         } | 
 |         return hash; | 
 |     } | 
 |  | 
 |     /** | 
 |      * <p>Appends the toString that would be produced by {@link Object} | 
 |      * if a class did not override toString itself. {@code null} | 
 |      * will throw a NullPointerException for either of the two parameters. </p> | 
 |      * | 
 |      * <pre> | 
 |      * ObjectUtils.identityToString(appendable, "")            = appendable.append("java.lang.String@1e23") | 
 |      * ObjectUtils.identityToString(appendable, Boolean.TRUE)  = appendable.append("java.lang.Boolean@7fa") | 
 |      * ObjectUtils.identityToString(appendable, Boolean.TRUE)  = appendable.append("java.lang.Boolean@7fa") | 
 |      * </pre> | 
 |      * | 
 |      * @param appendable  the appendable to append to | 
 |      * @param object  the object to create a toString for | 
 |      * @throws IOException if an I/O error occurs. | 
 |      * @since 3.2 | 
 |      */ | 
 |     public static void identityToString(final Appendable appendable, final Object object) throws IOException { | 
 |         Validate.notNull(object, "object"); | 
 |         appendable.append(object.getClass().getName()) | 
 |               .append(AT_SIGN) | 
 |               .append(identityHashCodeHex(object)); | 
 |     } | 
 |  | 
 |     /** | 
 |      * Returns the hex hash code for the given object per {@link System#identityHashCode(Object)}. | 
 |      * <p> | 
 |      * Short hand for {@code Integer.toHexString(System.identityHashCode(object))}. | 
 |      * </p> | 
 |      * | 
 |      * @param object object for which the hashCode is to be calculated | 
 |      * @return Hash code in hexadecimal format. | 
 |      * @since 3.13.0 | 
 |      */ | 
 |     public static String identityHashCodeHex(final Object object) { | 
 |         return Integer.toHexString(System.identityHashCode(object)); | 
 |     } | 
 |  | 
 |     /** | 
 |      * <p>Gets the toString that would be produced by {@link Object} | 
 |      * if a class did not override toString itself. {@code null} | 
 |      * will return {@code null}.</p> | 
 |      * | 
 |      * <pre> | 
 |      * ObjectUtils.identityToString(null)         = null | 
 |      * ObjectUtils.identityToString("")           = "java.lang.String@1e23" | 
 |      * ObjectUtils.identityToString(Boolean.TRUE) = "java.lang.Boolean@7fa" | 
 |      * </pre> | 
 |      * | 
 |      * @param object  the object to create a toString for, may be | 
 |      *  {@code null} | 
 |      * @return the default toString text, or {@code null} if | 
 |      *  {@code null} passed in | 
 |      */ | 
 |     public static String identityToString(final Object object) { | 
 |         if (object == null) { | 
 |             return null; | 
 |         } | 
 |         final String name = object.getClass().getName(); | 
 |         final String hexString = identityHashCodeHex(object); | 
 |         final StringBuilder builder = new StringBuilder(name.length() + 1 + hexString.length()); | 
 |         // @formatter:off | 
 |         builder.append(name) | 
 |               .append(AT_SIGN) | 
 |               .append(hexString); | 
 |         // @formatter:on | 
 |         return builder.toString(); | 
 |     } | 
 |  | 
 |     /** | 
 |      * <p>Appends the toString that would be produced by {@link Object} | 
 |      * if a class did not override toString itself. {@code null} | 
 |      * will throw a NullPointerException for either of the two parameters. </p> | 
 |      * | 
 |      * <pre> | 
 |      * ObjectUtils.identityToString(builder, "")            = builder.append("java.lang.String@1e23") | 
 |      * ObjectUtils.identityToString(builder, Boolean.TRUE)  = builder.append("java.lang.Boolean@7fa") | 
 |      * ObjectUtils.identityToString(builder, Boolean.TRUE)  = builder.append("java.lang.Boolean@7fa") | 
 |      * </pre> | 
 |      * | 
 |      * @param builder  the builder to append to | 
 |      * @param object  the object to create a toString for | 
 |      * @since 3.2 | 
 |      * @deprecated as of 3.6, because StrBuilder was moved to commons-text, | 
 |      *  use one of the other {@code identityToString} methods instead | 
 |      */ | 
 |     @Deprecated | 
 |     public static void identityToString(final StrBuilder builder, final Object object) { | 
 |         Validate.notNull(object, "object"); | 
 |         final String name = object.getClass().getName(); | 
 |         final String hexString = identityHashCodeHex(object); | 
 |         builder.ensureCapacity(builder.length() +  name.length() + 1 + hexString.length()); | 
 |         builder.append(name) | 
 |               .append(AT_SIGN) | 
 |               .append(hexString); | 
 |     } | 
 |  | 
 |     /** | 
 |      * <p>Appends the toString that would be produced by {@link Object} | 
 |      * if a class did not override toString itself. {@code null} | 
 |      * will throw a NullPointerException for either of the two parameters. </p> | 
 |      * | 
 |      * <pre> | 
 |      * ObjectUtils.identityToString(buf, "")            = buf.append("java.lang.String@1e23") | 
 |      * ObjectUtils.identityToString(buf, Boolean.TRUE)  = buf.append("java.lang.Boolean@7fa") | 
 |      * ObjectUtils.identityToString(buf, Boolean.TRUE)  = buf.append("java.lang.Boolean@7fa") | 
 |      * </pre> | 
 |      * | 
 |      * @param buffer  the buffer to append to | 
 |      * @param object  the object to create a toString for | 
 |      * @since 2.4 | 
 |      */ | 
 |     public static void identityToString(final StringBuffer buffer, final Object object) { | 
 |         Validate.notNull(object, "object"); | 
 |         final String name = object.getClass().getName(); | 
 |         final String hexString = identityHashCodeHex(object); | 
 |         buffer.ensureCapacity(buffer.length() + name.length() + 1 + hexString.length()); | 
 |         buffer.append(name) | 
 |               .append(AT_SIGN) | 
 |               .append(hexString); | 
 |     } | 
 |  | 
 |     /** | 
 |      * <p>Appends the toString that would be produced by {@link Object} | 
 |      * if a class did not override toString itself. {@code null} | 
 |      * will throw a NullPointerException for either of the two parameters. </p> | 
 |      * | 
 |      * <pre> | 
 |      * ObjectUtils.identityToString(builder, "")            = builder.append("java.lang.String@1e23") | 
 |      * ObjectUtils.identityToString(builder, Boolean.TRUE)  = builder.append("java.lang.Boolean@7fa") | 
 |      * ObjectUtils.identityToString(builder, Boolean.TRUE)  = builder.append("java.lang.Boolean@7fa") | 
 |      * </pre> | 
 |      * | 
 |      * @param builder  the builder to append to | 
 |      * @param object  the object to create a toString for | 
 |      * @since 3.2 | 
 |      */ | 
 |     public static void identityToString(final StringBuilder builder, final Object object) { | 
 |         Validate.notNull(object, "object"); | 
 |         final String name = object.getClass().getName(); | 
 |         final String hexString = identityHashCodeHex(object); | 
 |         builder.ensureCapacity(builder.length() +  name.length() + 1 + hexString.length()); | 
 |         builder.append(name) | 
 |               .append(AT_SIGN) | 
 |               .append(hexString); | 
 |     } | 
 |  | 
 |  | 
 |     // Constants (LANG-816): | 
 |     /* | 
 |         These methods ensure constants are not inlined by javac. | 
 |         For example, typically a developer might declare a constant like so: | 
 |  | 
 |             public final static int MAGIC_NUMBER = 5; | 
 |  | 
 |         Should a different jar file refer to this, and the MAGIC_NUMBER | 
 |         is changed a later date (e.g., MAGIC_NUMBER = 6), the different jar | 
 |         file will need to recompile itself.  This is because javac | 
 |         typically inlines the primitive or String constant directly into | 
 |         the bytecode, and removes the reference to the MAGIC_NUMBER field. | 
 |  | 
 |         To help the other jar (so that it does not need to recompile | 
 |         when constants are changed) the original developer can declare | 
 |         their constant using one of the CONST() utility methods, instead: | 
 |  | 
 |             public final static int MAGIC_NUMBER = CONST(5); | 
 |      */ | 
 |  | 
 |     /** | 
 |      * <p> | 
 |      * Checks, whether the given object is an Object array or a primitive array in a null-safe manner. | 
 |      * </p> | 
 |      * | 
 |      * <p> | 
 |      * A {@code null} {@code object} Object will return {@code false}. | 
 |      * </p> | 
 |      * | 
 |      * <pre> | 
 |      * ObjectUtils.isArray(null)             = false | 
 |      * ObjectUtils.isArray("")               = false | 
 |      * ObjectUtils.isArray("ab")             = false | 
 |      * ObjectUtils.isArray(new int[]{})      = true | 
 |      * ObjectUtils.isArray(new int[]{1,2,3}) = true | 
 |      * ObjectUtils.isArray(1234)             = false | 
 |      * </pre> | 
 |      * | 
 |      * @param object the object to check, may be {@code null} | 
 |      * @return {@code true} if the object is an {@code array}, {@code false} otherwise | 
 |      * @since 3.13.0 | 
 |      */ | 
 |     public static boolean isArray(final Object object) { | 
 |         return object != null && object.getClass().isArray(); | 
 |     } | 
 |  | 
 |     /** | 
 |      * <p>Checks if an Object is empty or null.</p> | 
 |      * | 
 |      * The following types are supported: | 
 |      * <ul> | 
 |      * <li>{@link CharSequence}: Considered empty if its length is zero.</li> | 
 |      * <li>{@link Array}: Considered empty if its length is zero.</li> | 
 |      * <li>{@link Collection}: Considered empty if it has zero elements.</li> | 
 |      * <li>{@link Map}: Considered empty if it has zero key-value mappings.</li> | 
 |      * </ul> | 
 |      * | 
 |      * <pre> | 
 |      * ObjectUtils.isEmpty(null)             = true | 
 |      * ObjectUtils.isEmpty("")               = true | 
 |      * ObjectUtils.isEmpty("ab")             = false | 
 |      * ObjectUtils.isEmpty(new int[]{})      = true | 
 |      * ObjectUtils.isEmpty(new int[]{1,2,3}) = false | 
 |      * ObjectUtils.isEmpty(1234)             = false | 
 |      * </pre> | 
 |      * | 
 |      * @param object  the {@link Object} to test, may be {@code null} | 
 |      * @return {@code true} if the object has a supported type and is empty or null, | 
 |      * {@code false} otherwise | 
 |      * @since 3.9 | 
 |      */ | 
 |     public static boolean isEmpty(final Object object) { | 
 |         if (object == null) { | 
 |             return true; | 
 |         } | 
 |         if (object instanceof CharSequence) { | 
 |             return ((CharSequence) object).length() == 0; | 
 |         } | 
 |         if (isArray(object)) { | 
 |             return Array.getLength(object) == 0; | 
 |         } | 
 |         if (object instanceof Collection<?>) { | 
 |             return ((Collection<?>) object).isEmpty(); | 
 |         } | 
 |         if (object instanceof Map<?, ?>) { | 
 |             return ((Map<?, ?>) object).isEmpty(); | 
 |         } | 
 |         return false; | 
 |     } | 
 |  | 
 |     /** | 
 |      * <p>Checks if an Object is not empty and not null.</p> | 
 |      * | 
 |      * The following types are supported: | 
 |      * <ul> | 
 |      * <li>{@link CharSequence}: Considered empty if its length is zero.</li> | 
 |      * <li>{@link Array}: Considered empty if its length is zero.</li> | 
 |      * <li>{@link Collection}: Considered empty if it has zero elements.</li> | 
 |      * <li>{@link Map}: Considered empty if it has zero key-value mappings.</li> | 
 |      * </ul> | 
 |      * | 
 |      * <pre> | 
 |      * ObjectUtils.isNotEmpty(null)             = false | 
 |      * ObjectUtils.isNotEmpty("")               = false | 
 |      * ObjectUtils.isNotEmpty("ab")             = true | 
 |      * ObjectUtils.isNotEmpty(new int[]{})      = false | 
 |      * ObjectUtils.isNotEmpty(new int[]{1,2,3}) = true | 
 |      * ObjectUtils.isNotEmpty(1234)             = true | 
 |      * </pre> | 
 |      * | 
 |      * @param object  the {@link Object} to test, may be {@code null} | 
 |      * @return {@code true} if the object has an unsupported type or is not empty | 
 |      * and not null, {@code false} otherwise | 
 |      * @since 3.9 | 
 |      */ | 
 |     public static boolean isNotEmpty(final Object object) { | 
 |         return !isEmpty(object); | 
 |     } | 
 |  | 
 |     /** | 
 |      * <p>Null safe comparison of Comparables.</p> | 
 |      * <p>TODO Move to ComparableUtils.</p> | 
 |      * | 
 |      * @param <T> type of the values processed by this method | 
 |      * @param values the set of comparable values, may be null | 
 |      * @return | 
 |      *  <ul> | 
 |      *   <li>If any objects are non-null and unequal, the greater object. | 
 |      *   <li>If all objects are non-null and equal, the first. | 
 |      *   <li>If any of the comparables are null, the greater of the non-null objects. | 
 |      *   <li>If all the comparables are null, null is returned. | 
 |      *  </ul> | 
 |      */ | 
 |     @SafeVarargs | 
 |     public static <T extends Comparable<? super T>> T max(final T... values) { | 
 |         T result = null; | 
 |         if (values != null) { | 
 |             for (final T value : values) { | 
 |                 if (compare(value, result, false) > 0) { | 
 |                     result = value; | 
 |                 } | 
 |             } | 
 |         } | 
 |         return result; | 
 |     } | 
 |  | 
 |     /** | 
 |      * Find the "best guess" middle value among comparables. If there is an even | 
 |      * number of total values, the lower of the two middle values will be returned. | 
 |      * @param <T> type of values processed by this method | 
 |      * @param comparator to use for comparisons | 
 |      * @param items to compare | 
 |      * @return T at middle position | 
 |      * @throws NullPointerException if items or comparator is {@code null} | 
 |      * @throws IllegalArgumentException if items is empty or contains {@code null} values | 
 |      * @since 3.0.1 | 
 |      */ | 
 |     @SafeVarargs | 
 |     public static <T> T median(final Comparator<T> comparator, final T... items) { | 
 |         Validate.notEmpty(items, "null/empty items"); | 
 |         Validate.noNullElements(items); | 
 |         Validate.notNull(comparator, "comparator"); | 
 |         final TreeSet<T> treeSet = new TreeSet<>(comparator); | 
 |         Collections.addAll(treeSet, items); | 
 |         @SuppressWarnings("unchecked") //we know all items added were T instances | 
 |         final T result = (T) treeSet.toArray()[(treeSet.size() - 1) / 2]; | 
 |         return result; | 
 |     } | 
 |  | 
 |     /** | 
 |      * Find the "best guess" middle value among comparables. If there is an even | 
 |      * number of total values, the lower of the two middle values will be returned. | 
 |      * @param <T> type of values processed by this method | 
 |      * @param items to compare | 
 |      * @return T at middle position | 
 |      * @throws NullPointerException if items is {@code null} | 
 |      * @throws IllegalArgumentException if items is empty or contains {@code null} values | 
 |      * @since 3.0.1 | 
 |      */ | 
 |     @SafeVarargs | 
 |     public static <T extends Comparable<? super T>> T median(final T... items) { | 
 |         Validate.notEmpty(items); | 
 |         Validate.noNullElements(items); | 
 |         final TreeSet<T> sort = new TreeSet<>(); | 
 |         Collections.addAll(sort, items); | 
 |         @SuppressWarnings("unchecked") //we know all items added were T instances | 
 |         final T result = (T) sort.toArray()[(sort.size() - 1) / 2]; | 
 |         return result; | 
 |     } | 
 |  | 
 |     /** | 
 |      * <p>Null safe comparison of Comparables.</p> | 
 |      * <p>TODO Move to ComparableUtils.</p> | 
 |      * | 
 |      * @param <T> type of the values processed by this method | 
 |      * @param values the set of comparable values, may be null | 
 |      * @return | 
 |      *  <ul> | 
 |      *   <li>If any objects are non-null and unequal, the lesser object. | 
 |      *   <li>If all objects are non-null and equal, the first. | 
 |      *   <li>If any of the comparables are null, the lesser of the non-null objects. | 
 |      *   <li>If all the comparables are null, null is returned. | 
 |      *  </ul> | 
 |      */ | 
 |     @SafeVarargs | 
 |     public static <T extends Comparable<? super T>> T min(final T... values) { | 
 |         T result = null; | 
 |         if (values != null) { | 
 |             for (final T value : values) { | 
 |                 if (compare(value, result, true) < 0) { | 
 |                     result = value; | 
 |                 } | 
 |             } | 
 |         } | 
 |         return result; | 
 |     } | 
 |  | 
 |  | 
 |     /** | 
 |      * Find the most frequently occurring item. | 
 |      * | 
 |      * @param <T> type of values processed by this method | 
 |      * @param items to check | 
 |      * @return most populous T, {@code null} if non-unique or no items supplied | 
 |      * @since 3.0.1 | 
 |      */ | 
 |     @SafeVarargs | 
 |     public static <T> T mode(final T... items) { | 
 |         if (ArrayUtils.isNotEmpty(items)) { | 
 |             final HashMap<T, MutableInt> occurrences = new HashMap<>(items.length); | 
 |             for (final T t : items) { | 
 |                 final MutableInt count = occurrences.get(t); | 
 |                 if (count == null) { | 
 |                     occurrences.put(t, new MutableInt(1)); | 
 |                 } else { | 
 |                     count.increment(); | 
 |                 } | 
 |             } | 
 |             T result = null; | 
 |             int max = 0; | 
 |             for (final Map.Entry<T, MutableInt> e : occurrences.entrySet()) { | 
 |                 final int cmp = e.getValue().intValue(); | 
 |                 if (cmp == max) { | 
 |                     result = null; | 
 |                 } else if (cmp > max) { | 
 |                     max = cmp; | 
 |                     result = e.getKey(); | 
 |                 } | 
 |             } | 
 |             return result; | 
 |         } | 
 |         return null; | 
 |     } | 
 |  | 
 |     /** | 
 |      * <p>Compares two objects for inequality, where either one or both | 
 |      * objects may be {@code null}.</p> | 
 |      * | 
 |      * <pre> | 
 |      * ObjectUtils.notEqual(null, null)                  = false | 
 |      * ObjectUtils.notEqual(null, "")                    = true | 
 |      * ObjectUtils.notEqual("", null)                    = true | 
 |      * ObjectUtils.notEqual("", "")                      = false | 
 |      * ObjectUtils.notEqual(Boolean.TRUE, null)          = true | 
 |      * ObjectUtils.notEqual(Boolean.TRUE, "true")        = true | 
 |      * ObjectUtils.notEqual(Boolean.TRUE, Boolean.TRUE)  = false | 
 |      * ObjectUtils.notEqual(Boolean.TRUE, Boolean.FALSE) = true | 
 |      * </pre> | 
 |      * | 
 |      * @param object1  the first object, may be {@code null} | 
 |      * @param object2  the second object, may be {@code null} | 
 |      * @return {@code false} if the values of both objects are the same | 
 |      */ | 
 |     public static boolean notEqual(final Object object1, final Object object2) { | 
 |         return !Objects.equals(object1, object2); | 
 |     } | 
 |  | 
 |     /** | 
 |      * Checks that the specified object reference is not {@code null} or empty per {@link #isEmpty(Object)}. Use this | 
 |      * method for validation, for example: | 
 |      * | 
 |      * <blockquote> | 
 |      * | 
 |      * <pre> | 
 |      * public Foo(Bar bar) { | 
 |      *     this.bar = Objects.requireNonEmpty(bar); | 
 |      * } | 
 |      * </pre> | 
 |      * | 
 |      * </blockquote> | 
 |      * | 
 |      * @param <T> the type of the reference. | 
 |      * @param obj the object reference to check for nullity. | 
 |      * @return {@code obj} if not {@code null}. | 
 |      * @throws NullPointerException     if {@code obj} is {@code null}. | 
 |      * @throws IllegalArgumentException if {@code obj} is empty per {@link #isEmpty(Object)}. | 
 |      * @see #isEmpty(Object) | 
 |      * @since 3.12.0 | 
 |      */ | 
 |     public static <T> T  requireNonEmpty(final T obj) { | 
 |         return requireNonEmpty(obj, "object"); | 
 |     } | 
 |  | 
 |     /** | 
 |      * Checks that the specified object reference is not {@code null} or empty per {@link #isEmpty(Object)}. Use this | 
 |      * method for validation, for example: | 
 |      * | 
 |      * <blockquote> | 
 |      * | 
 |      * <pre> | 
 |      * public Foo(Bar bar) { | 
 |      *     this.bar = Objects.requireNonEmpty(bar, "bar"); | 
 |      * } | 
 |      * </pre> | 
 |      * | 
 |      * </blockquote> | 
 |      * | 
 |      * @param <T> the type of the reference. | 
 |      * @param obj the object reference to check for nullity. | 
 |      * @param message the exception message. | 
 |      * @return {@code obj} if not {@code null}. | 
 |      * @throws NullPointerException     if {@code obj} is {@code null}. | 
 |      * @throws IllegalArgumentException if {@code obj} is empty per {@link #isEmpty(Object)}. | 
 |      * @see #isEmpty(Object) | 
 |      * @since 3.12.0 | 
 |      */ | 
 |     public static <T> T requireNonEmpty(final T obj, final String message) { | 
 |         // check for null first to give the most precise exception. | 
 |         Objects.requireNonNull(obj, message); | 
 |         if (isEmpty(obj)) { | 
 |             throw new IllegalArgumentException(message); | 
 |         } | 
 |         return obj; | 
 |     } | 
 |  | 
 |     /** | 
 |      * <p>Gets the {@code toString} of an {@link Object} returning | 
 |      * an empty string ("") if {@code null} input.</p> | 
 |      * | 
 |      * <pre> | 
 |      * ObjectUtils.toString(null)         = "" | 
 |      * ObjectUtils.toString("")           = "" | 
 |      * ObjectUtils.toString("bat")        = "bat" | 
 |      * ObjectUtils.toString(Boolean.TRUE) = "true" | 
 |      * </pre> | 
 |      * | 
 |      * @see StringUtils#defaultString(String) | 
 |      * @see String#valueOf(Object) | 
 |      * @param obj  the Object to {@code toString}, may be null | 
 |      * @return the passed in Object's toString, or {@code ""} if {@code null} input | 
 |      * @since 2.0 | 
 |      * @deprecated this method has been replaced by {@code java.util.Objects.toString(Object)} in Java 7 and will be | 
 |      * removed in future releases. Note however that said method will return "null" for null references, while this | 
 |      * method returns an empty String. To preserve behavior use {@code java.util.Objects.toString(myObject, "")} | 
 |      */ | 
 |     @Deprecated | 
 |     public static String toString(final Object obj) { | 
 |         return obj == null ? StringUtils.EMPTY : obj.toString(); | 
 |     } | 
 |  | 
 |     /** | 
 |      * <p>Gets the {@code toString} of an {@link Object} returning | 
 |      * a specified text if {@code null} input.</p> | 
 |      * | 
 |      * <pre> | 
 |      * ObjectUtils.toString(null, null)           = null | 
 |      * ObjectUtils.toString(null, "null")         = "null" | 
 |      * ObjectUtils.toString("", "null")           = "" | 
 |      * ObjectUtils.toString("bat", "null")        = "bat" | 
 |      * ObjectUtils.toString(Boolean.TRUE, "null") = "true" | 
 |      * </pre> | 
 |      * | 
 |      * @see StringUtils#defaultString(String,String) | 
 |      * @see String#valueOf(Object) | 
 |      * @param obj  the Object to {@code toString}, may be null | 
 |      * @param nullStr  the String to return if {@code null} input, may be null | 
 |      * @return the passed in Object's toString, or {@code nullStr} if {@code null} input | 
 |      * @since 2.0 | 
 |      * @deprecated this method has been replaced by {@code java.util.Objects.toString(Object, String)} in Java 7 and | 
 |      * will be removed in future releases. | 
 |      */ | 
 |     @Deprecated | 
 |     public static String toString(final Object obj, final String nullStr) { | 
 |         return obj == null ? nullStr : obj.toString(); | 
 |     } | 
 |  | 
 |     /** | 
 |      * <p>Gets the {@code toString} of an {@link Object} returning | 
 |      * a specified text if {@code null} input.</p> | 
 |      * | 
 |      * <pre> | 
 |      * ObjectUtils.toString(obj, () -> expensive()) | 
 |      * </pre> | 
 |      * <pre> | 
 |      * ObjectUtils.toString(null, () -> expensive())         = result of expensive() | 
 |      * ObjectUtils.toString(null, () -> expensive())         = result of expensive() | 
 |      * ObjectUtils.toString("", () -> expensive())           = "" | 
 |      * ObjectUtils.toString("bat", () -> expensive())        = "bat" | 
 |      * ObjectUtils.toString(Boolean.TRUE, () -> expensive()) = "true" | 
 |      * </pre> | 
 |      * | 
 |      * @param obj  the Object to {@code toString}, may be null | 
 |      * @param supplier  the Supplier of String used on {@code null} input, may be null | 
 |      * @return the passed in Object's toString, or {@code nullStr} if {@code null} input | 
 |      * @since 3.11 | 
 |      */ | 
 |     public static String toString(final Object obj, final Supplier<String> supplier) { | 
 |         return obj == null ? Suppliers.get(supplier) : obj.toString(); | 
 |     } | 
 |  | 
 |     /** | 
 |      * Calls {@link Object#wait(long, int)} for the given Duration. | 
 |      * | 
 |      * @param obj The receiver of the wait call. | 
 |      * @param duration How long to wait. | 
 |      * @throws IllegalArgumentException if the timeout duration is negative. | 
 |      * @throws IllegalMonitorStateException if the current thread is not the owner of the {@code obj}'s monitor. | 
 |      * @throws InterruptedException if any thread interrupted the current thread before or while the current thread was | 
 |      *         waiting for a notification. The <em>interrupted status</em> of the current thread is cleared when this | 
 |      *         exception is thrown. | 
 |      * @see Object#wait(long, int) | 
 |      * @since 3.12.0 | 
 |      */ | 
 |     public static void wait(final Object obj, final Duration duration) throws InterruptedException { | 
 |         DurationUtils.accept(obj::wait, DurationUtils.zeroIfNull(duration)); | 
 |     } | 
 |  | 
 |     /** | 
 |      * <p>{@link ObjectUtils} instances should NOT be constructed in | 
 |      * standard programming. Instead, the static methods on the class should | 
 |      * be used, such as {@code ObjectUtils.defaultIfNull("a","b");}.</p> | 
 |      * | 
 |      * <p>This constructor is public to permit tools that require a JavaBean | 
 |      * instance to operate.</p> | 
 |      */ | 
 |     public ObjectUtils() { | 
 |     } | 
 |  | 
 | } |