From ccaab5d0b312b28ab15833ab8f11dd809ec93aab Mon Sep 17 00:00:00 2001 From: Samuel Tardieu Date: Wed, 14 Sep 2011 23:54:46 +0200 Subject: Convert to Unix end-of-line format --- src/org/apache/commons/lang3/ObjectUtils.java | 1216 ++++++++++++------------- 1 file changed, 608 insertions(+), 608 deletions(-) (limited to 'src/org/apache/commons/lang3/ObjectUtils.java') diff --git a/src/org/apache/commons/lang3/ObjectUtils.java b/src/org/apache/commons/lang3/ObjectUtils.java index 69dde6f..a75184c 100644 --- a/src/org/apache/commons/lang3/ObjectUtils.java +++ b/src/org/apache/commons/lang3/ObjectUtils.java @@ -1,608 +1,608 @@ -/* - * 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.Serializable; -import java.lang.reflect.Array; -import java.lang.reflect.InvocationTargetException; -import java.lang.reflect.Method; -import java.util.Collections; -import java.util.Comparator; -import java.util.HashMap; -import java.util.Map; -import java.util.TreeSet; - -import org.apache.commons.lang3.exception.CloneFailedException; -import org.apache.commons.lang3.mutable.MutableInt; - -/** - *

Operations on {@code Object}.

- * - *

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 behaviour in more detail.

- * - *

#ThreadSafe#

- * @since 1.0 - * @version $Id: ObjectUtils.java 1153350 2011-08-03 05:29:21Z bayard $ - */ -//@Immutable -public class ObjectUtils { - - /** - *

Singleton used as a {@code null} placeholder where - * {@code null} has another meaning.

- * - *

For example, in a {@code HashMap} the - * {@link java.util.HashMap#get(java.lang.Object)} method returns - * {@code null} if the {@code Map} contains {@code null} or if there - * is no matching key. The {@code Null} placeholder can be used to - * distinguish between these two cases.

- * - *

Another example is {@code Hashtable}, where {@code null} - * cannot be stored.

- * - *

This instance is Serializable.

- */ - public static final Null NULL = new Null(); - - /** - *

{@code 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");}.

- * - *

This constructor is public to permit tools that require a JavaBean - * instance to operate.

- */ - public ObjectUtils() { - super(); - } - - // Defaulting - //----------------------------------------------------------------------- - /** - *

Returns a default value if the object passed is {@code null}.

- * - * 
-     * ObjectUtils.defaultIfNull(null, null)      = null
-     * ObjectUtils.defaultIfNull(null, "")        = ""
-     * ObjectUtils.defaultIfNull(null, "zz")      = "zz"
-     * ObjectUtils.defaultIfNull("abc", *)        = "abc"
-     * ObjectUtils.defaultIfNull(Boolean.TRUE, *) = Boolean.TRUE
-     *
- * - * @param the type of the object - * @param object the {@code 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 - */ - public static T defaultIfNull(T object, T defaultValue) { - return object != null ? object : defaultValue; - } - - /** - *

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.

- * - * 
-     * 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
-     *
- * - * @param 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 - */ - public static T firstNonNull(T... values) { - if (values != null) { - for (T val : values) { - if (val != null) { - return val; - } - } - } - return null; - } - - // Null-safe equals/hashCode - //----------------------------------------------------------------------- - /** - *

Compares two objects for equality, where either one or both - * objects may be {@code null}.

- * - * 
-     * 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
-     *
- * - * @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 - */ - public static boolean equals(Object object1, Object object2) { - if (object1 == object2) { - return true; - } - if ((object1 == null) || (object2 == null)) { - return false; - } - return object1.equals(object2); - } - - /** - *

Compares two objects for inequality, where either one or both - * objects may be {@code null}.

- * - * 
-     * 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
-     *
- * - * @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(Object object1, Object object2) { - return ObjectUtils.equals(object1, object2) == false; - } - - /** - *

Gets the hash code of an object returning zero when the - * object is {@code null}.

- * - * 
-     * ObjectUtils.hashCode(null)   = 0
-     * ObjectUtils.hashCode(obj)    = obj.hashCode()
-     *
- * - * @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 - */ - public static int hashCode(Object obj) { - // hashCode(Object) retained for performance, as hash code is often critical - return (obj == null) ? 0 : obj.hashCode(); - } - - /** - *

Gets the hash code for multiple objects.

- * - *

This allows a hash code to be rapidly calculated for a number of objects. - * The hash code for a single object is the not same as {@link #hashCode(Object)}. - * The hash code for multiple objects is the same as that calculated by an - * {@code ArrayList} containing the specified objects.

- * - * 
-     * 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()
-     *
- * - * @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 - */ - public static int hashCodeMulti(Object... objects) { - int hash = 1; - if (objects != null) { - for (Object object : objects) { - hash = hash * 31 + ObjectUtils.hashCode(object); - } - } - return hash; - } - - // Identity ToString - //----------------------------------------------------------------------- - /** - *

Gets the toString that would be produced by {@code Object} - * if a class did not override toString itself. {@code null} - * will return {@code null}.

- * - * 
-     * ObjectUtils.identityToString(null)         = null
-     * ObjectUtils.identityToString("")           = "java.lang.String@1e23"
-     * ObjectUtils.identityToString(Boolean.TRUE) = "java.lang.Boolean@7fa"
-     *
- * - * @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(Object object) { - if (object == null) { - return null; - } - StringBuffer buffer = new StringBuffer(); - identityToString(buffer, object); - return buffer.toString(); - } - - /** - *

Appends the toString that would be produced by {@code Object} - * if a class did not override toString itself. {@code null} - * will throw a NullPointerException for either of the two parameters.

- * - * 
-     * 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")
-     *
- * - * @param buffer the buffer to append to - * @param object the object to create a toString for - * @since 2.4 - */ - public static void identityToString(StringBuffer buffer, Object object) { - if (object == null) { - throw new NullPointerException("Cannot get the toString of a null identity"); - } - buffer.append(object.getClass().getName()) - .append('@') - .append(Integer.toHexString(System.identityHashCode(object))); - } - - // ToString - //----------------------------------------------------------------------- - /** - *

Gets the {@code toString} of an {@code Object} returning - * an empty string ("") if {@code null} input.

- * - * 
-     * ObjectUtils.toString(null)         = ""
-     * ObjectUtils.toString("")           = ""
-     * ObjectUtils.toString("bat")        = "bat"
-     * ObjectUtils.toString(Boolean.TRUE) = "true"
-     *
- * - * @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 nullStr if {@code null} input - * @since 2.0 - */ - public static String toString(Object obj) { - return obj == null ? "" : obj.toString(); - } - - /** - *

Gets the {@code toString} of an {@code Object} returning - * a specified text if {@code null} input.

- * - * 
-     * ObjectUtils.toString(null, null)           = null
-     * ObjectUtils.toString(null, "null")         = "null"
-     * ObjectUtils.toString("", "null")           = ""
-     * ObjectUtils.toString("bat", "null")        = "bat"
-     * ObjectUtils.toString(Boolean.TRUE, "null") = "true"
-     *
- * - * @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 nullStr if {@code null} input - * @since 2.0 - */ - public static String toString(Object obj, String nullStr) { - return obj == null ? nullStr : obj.toString(); - } - - // Comparable - //----------------------------------------------------------------------- - /** - *

Null safe comparison of Comparables.

- * - * @param type of the values processed by this method - * @param values the set of comparable values, may be null - * @return - *
    - *
  • If any objects are non-null and unequal, the lesser object. - *
  • If all objects are non-null and equal, the first. - *
  • If any of the comparables are null, the lesser of the non-null objects. - *
  • If all the comparables are null, null is returned. - *
- */ - public static > T min(T... values) { - T result = null; - if (values != null) { - for (T value : values) { - if (compare(value, result, true) < 0) { - result = value; - } - } - } - return result; - } - - /** - *

Null safe comparison of Comparables.

- * - * @param type of the values processed by this method - * @param values the set of comparable values, may be null - * @return - *
    - *
  • If any objects are non-null and unequal, the greater object. - *
  • If all objects are non-null and equal, the first. - *
  • If any of the comparables are null, the greater of the non-null objects. - *
  • If all the comparables are null, null is returned. - *
- */ - public static > T max(T... values) { - T result = null; - if (values != null) { - for (T value : values) { - if (compare(value, result, false) > 0) { - result = value; - } - } - } - return result; - } - - /** - *

Null safe comparison of Comparables. - * {@code null} is assumed to be less than a non-{@code null} value.

- * - * @param 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 > int compare(T c1, T c2) { - return compare(c1, c2, false); - } - - /** - *

Null safe comparison of Comparables.

- * - * @param 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 > int compare(T c1, T c2, boolean nullGreater) { - if (c1 == c2) { - return 0; - } else if (c1 == null) { - return (nullGreater ? 1 : -1); - } else if (c2 == null) { - return (nullGreater ? -1 : 1); - } - return c1.compareTo(c2); - } - - /** - * 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 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 - */ - public static > T median(T... items) { - Validate.notEmpty(items); - Validate.noNullElements(items); - TreeSet sort = new TreeSet(); - Collections.addAll(sort, items); - @SuppressWarnings("unchecked") //we know all items added were T instances - T result = (T) sort.toArray()[(sort.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 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 - */ - public static T median(Comparator comparator, T... items) { - Validate.notEmpty(items, "null/empty items"); - Validate.noNullElements(items); - Validate.notNull(comparator, "null comparator"); - TreeSet sort = new TreeSet(comparator); - Collections.addAll(sort, items); - @SuppressWarnings("unchecked") //we know all items added were T instances - T result = (T) sort.toArray()[(sort.size() - 1) / 2]; - return result; - } - - // Mode - //----------------------------------------------------------------------- - /** - * Find the most frequently occurring item. - * - * @param 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 - */ - public static T mode(T... items) { - if (ArrayUtils.isNotEmpty(items)) { - HashMap occurrences = new HashMap(items.length); - for (T t : items) { - MutableInt count = occurrences.get(t); - if (count == null) { - occurrences.put(t, new MutableInt(1)); - } else { - count.increment(); - } - } - T result = null; - int max = 0; - for (Map.Entry e : occurrences.entrySet()) { - int cmp = e.getValue().intValue(); - if (cmp == max) { - result = null; - } else if (cmp > max) { - max = cmp; - result = e.getKey(); - } - } - return result; - } - return null; - } - - // cloning - //----------------------------------------------------------------------- - /** - *

Clone an object.

- * - * @param 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 clone(final T obj) { - if (obj instanceof Cloneable) { - final Object result; - if (obj.getClass().isArray()) { - final Class componentType = obj.getClass().getComponentType(); - if (!componentType.isPrimitive()) { - result = ((Object[]) obj).clone(); - } else { - int length = Array.getLength(obj); - result = Array.newInstance(componentType, length); - while (length-- > 0) { - Array.set(result, length, Array.get(obj, length)); - } - } - } 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") - final T checked = (T) result; - return checked; - } - - return null; - } - - /** - *

Clone an object if possible.

- * - *

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.

- * - * @param 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 cloneIfPossible(final T obj) { - final T clone = clone(obj); - return clone == null ? obj : clone; - } - - // Null - //----------------------------------------------------------------------- - /** - *

Class used as a null placeholder where {@code null} - * has another meaning.

- * - *

For example, in a {@code HashMap} the - * {@link java.util.HashMap#get(java.lang.Object)} method returns - * {@code null} if the {@code Map} contains {@code null} or if there is - * no matching key. The {@code Null} placeholder can be used to distinguish - * between these two cases.

- * - *

Another example is {@code Hashtable}, where {@code null} - * cannot be stored.

- */ - 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() { - super(); - } - - /** - *

Ensure singleton.

- * - * @return the singleton value - */ - private Object readResolve() { - return ObjectUtils.NULL; - } - } - -} +/* + * 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.Serializable; +import java.lang.reflect.Array; +import java.lang.reflect.InvocationTargetException; +import java.lang.reflect.Method; +import java.util.Collections; +import java.util.Comparator; +import java.util.HashMap; +import java.util.Map; +import java.util.TreeSet; + +import org.apache.commons.lang3.exception.CloneFailedException; +import org.apache.commons.lang3.mutable.MutableInt; + +/** + *

Operations on {@code Object}.

+ * + *

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 behaviour in more detail.

+ * + *

#ThreadSafe#

+ * @since 1.0 + * @version $Id: ObjectUtils.java 1153350 2011-08-03 05:29:21Z bayard $ + */ +//@Immutable +public class ObjectUtils { + + /** + *

Singleton used as a {@code null} placeholder where + * {@code null} has another meaning.

+ * + *

For example, in a {@code HashMap} the + * {@link java.util.HashMap#get(java.lang.Object)} method returns + * {@code null} if the {@code Map} contains {@code null} or if there + * is no matching key. The {@code Null} placeholder can be used to + * distinguish between these two cases.

+ * + *

Another example is {@code Hashtable}, where {@code null} + * cannot be stored.

+ * + *

This instance is Serializable.

+ */ + public static final Null NULL = new Null(); + + /** + *

{@code 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");}.

+ * + *

This constructor is public to permit tools that require a JavaBean + * instance to operate.

+ */ + public ObjectUtils() { + super(); + } + + // Defaulting + //----------------------------------------------------------------------- + /** + *

Returns a default value if the object passed is {@code null}.

+ * + * 
+     * ObjectUtils.defaultIfNull(null, null)      = null
+     * ObjectUtils.defaultIfNull(null, "")        = ""
+     * ObjectUtils.defaultIfNull(null, "zz")      = "zz"
+     * ObjectUtils.defaultIfNull("abc", *)        = "abc"
+     * ObjectUtils.defaultIfNull(Boolean.TRUE, *) = Boolean.TRUE
+     *
+ * + * @param the type of the object + * @param object the {@code 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 + */ + public static T defaultIfNull(T object, T defaultValue) { + return object != null ? object : defaultValue; + } + + /** + *

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.

+ * + * 
+     * 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
+     *
+ * + * @param 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 + */ + public static T firstNonNull(T... values) { + if (values != null) { + for (T val : values) { + if (val != null) { + return val; + } + } + } + return null; + } + + // Null-safe equals/hashCode + //----------------------------------------------------------------------- + /** + *

Compares two objects for equality, where either one or both + * objects may be {@code null}.

+ * + * 
+     * 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
+     *
+ * + * @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 + */ + public static boolean equals(Object object1, Object object2) { + if (object1 == object2) { + return true; + } + if ((object1 == null) || (object2 == null)) { + return false; + } + return object1.equals(object2); + } + + /** + *

Compares two objects for inequality, where either one or both + * objects may be {@code null}.

+ * + * 
+     * 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
+     *
+ * + * @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(Object object1, Object object2) { + return ObjectUtils.equals(object1, object2) == false; + } + + /** + *

Gets the hash code of an object returning zero when the + * object is {@code null}.

+ * + * 
+     * ObjectUtils.hashCode(null)   = 0
+     * ObjectUtils.hashCode(obj)    = obj.hashCode()
+     *
+ * + * @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 + */ + public static int hashCode(Object obj) { + // hashCode(Object) retained for performance, as hash code is often critical + return (obj == null) ? 0 : obj.hashCode(); + } + + /** + *

Gets the hash code for multiple objects.

+ * + *

This allows a hash code to be rapidly calculated for a number of objects. + * The hash code for a single object is the not same as {@link #hashCode(Object)}. + * The hash code for multiple objects is the same as that calculated by an + * {@code ArrayList} containing the specified objects.

+ * + * 
+     * 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()
+     *
+ * + * @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 + */ + public static int hashCodeMulti(Object... objects) { + int hash = 1; + if (objects != null) { + for (Object object : objects) { + hash = hash * 31 + ObjectUtils.hashCode(object); + } + } + return hash; + } + + // Identity ToString + //----------------------------------------------------------------------- + /** + *

Gets the toString that would be produced by {@code Object} + * if a class did not override toString itself. {@code null} + * will return {@code null}.

+ * + * 
+     * ObjectUtils.identityToString(null)         = null
+     * ObjectUtils.identityToString("")           = "java.lang.String@1e23"
+     * ObjectUtils.identityToString(Boolean.TRUE) = "java.lang.Boolean@7fa"
+     *
+ * + * @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(Object object) { + if (object == null) { + return null; + } + StringBuffer buffer = new StringBuffer(); + identityToString(buffer, object); + return buffer.toString(); + } + + /** + *

Appends the toString that would be produced by {@code Object} + * if a class did not override toString itself. {@code null} + * will throw a NullPointerException for either of the two parameters.

+ * + * 
+     * 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")
+     *
+ * + * @param buffer the buffer to append to + * @param object the object to create a toString for + * @since 2.4 + */ + public static void identityToString(StringBuffer buffer, Object object) { + if (object == null) { + throw new NullPointerException("Cannot get the toString of a null identity"); + } + buffer.append(object.getClass().getName()) + .append('@') + .append(Integer.toHexString(System.identityHashCode(object))); + } + + // ToString + //----------------------------------------------------------------------- + /** + *

Gets the {@code toString} of an {@code Object} returning + * an empty string ("") if {@code null} input.

+ * + * 
+     * ObjectUtils.toString(null)         = ""
+     * ObjectUtils.toString("")           = ""
+     * ObjectUtils.toString("bat")        = "bat"
+     * ObjectUtils.toString(Boolean.TRUE) = "true"
+     *
+ * + * @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 nullStr if {@code null} input + * @since 2.0 + */ + public static String toString(Object obj) { + return obj == null ? "" : obj.toString(); + } + + /** + *

Gets the {@code toString} of an {@code Object} returning + * a specified text if {@code null} input.

+ * + * 
+     * ObjectUtils.toString(null, null)           = null
+     * ObjectUtils.toString(null, "null")         = "null"
+     * ObjectUtils.toString("", "null")           = ""
+     * ObjectUtils.toString("bat", "null")        = "bat"
+     * ObjectUtils.toString(Boolean.TRUE, "null") = "true"
+     *
+ * + * @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 nullStr if {@code null} input + * @since 2.0 + */ + public static String toString(Object obj, String nullStr) { + return obj == null ? nullStr : obj.toString(); + } + + // Comparable + //----------------------------------------------------------------------- + /** + *

Null safe comparison of Comparables.

+ * + * @param type of the values processed by this method + * @param values the set of comparable values, may be null + * @return + *
    + *
  • If any objects are non-null and unequal, the lesser object. + *
  • If all objects are non-null and equal, the first. + *
  • If any of the comparables are null, the lesser of the non-null objects. + *
  • If all the comparables are null, null is returned. + *
+ */ + public static > T min(T... values) { + T result = null; + if (values != null) { + for (T value : values) { + if (compare(value, result, true) < 0) { + result = value; + } + } + } + return result; + } + + /** + *

Null safe comparison of Comparables.

+ * + * @param type of the values processed by this method + * @param values the set of comparable values, may be null + * @return + *
    + *
  • If any objects are non-null and unequal, the greater object. + *
  • If all objects are non-null and equal, the first. + *
  • If any of the comparables are null, the greater of the non-null objects. + *
  • If all the comparables are null, null is returned. + *
+ */ + public static > T max(T... values) { + T result = null; + if (values != null) { + for (T value : values) { + if (compare(value, result, false) > 0) { + result = value; + } + } + } + return result; + } + + /** + *

Null safe comparison of Comparables. + * {@code null} is assumed to be less than a non-{@code null} value.

+ * + * @param 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 > int compare(T c1, T c2) { + return compare(c1, c2, false); + } + + /** + *

Null safe comparison of Comparables.

+ * + * @param 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 > int compare(T c1, T c2, boolean nullGreater) { + if (c1 == c2) { + return 0; + } else if (c1 == null) { + return (nullGreater ? 1 : -1); + } else if (c2 == null) { + return (nullGreater ? -1 : 1); + } + return c1.compareTo(c2); + } + + /** + * 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 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 + */ + public static > T median(T... items) { + Validate.notEmpty(items); + Validate.noNullElements(items); + TreeSet sort = new TreeSet(); + Collections.addAll(sort, items); + @SuppressWarnings("unchecked") //we know all items added were T instances + T result = (T) sort.toArray()[(sort.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 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 + */ + public static T median(Comparator comparator, T... items) { + Validate.notEmpty(items, "null/empty items"); + Validate.noNullElements(items); + Validate.notNull(comparator, "null comparator"); + TreeSet sort = new TreeSet(comparator); + Collections.addAll(sort, items); + @SuppressWarnings("unchecked") //we know all items added were T instances + T result = (T) sort.toArray()[(sort.size() - 1) / 2]; + return result; + } + + // Mode + //----------------------------------------------------------------------- + /** + * Find the most frequently occurring item. + * + * @param 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 + */ + public static T mode(T... items) { + if (ArrayUtils.isNotEmpty(items)) { + HashMap occurrences = new HashMap(items.length); + for (T t : items) { + MutableInt count = occurrences.get(t); + if (count == null) { + occurrences.put(t, new MutableInt(1)); + } else { + count.increment(); + } + } + T result = null; + int max = 0; + for (Map.Entry e : occurrences.entrySet()) { + int cmp = e.getValue().intValue(); + if (cmp == max) { + result = null; + } else if (cmp > max) { + max = cmp; + result = e.getKey(); + } + } + return result; + } + return null; + } + + // cloning + //----------------------------------------------------------------------- + /** + *

Clone an object.

+ * + * @param 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 clone(final T obj) { + if (obj instanceof Cloneable) { + final Object result; + if (obj.getClass().isArray()) { + final Class componentType = obj.getClass().getComponentType(); + if (!componentType.isPrimitive()) { + result = ((Object[]) obj).clone(); + } else { + int length = Array.getLength(obj); + result = Array.newInstance(componentType, length); + while (length-- > 0) { + Array.set(result, length, Array.get(obj, length)); + } + } + } 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") + final T checked = (T) result; + return checked; + } + + return null; + } + + /** + *

Clone an object if possible.

+ * + *

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.

+ * + * @param 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 cloneIfPossible(final T obj) { + final T clone = clone(obj); + return clone == null ? obj : clone; + } + + // Null + //----------------------------------------------------------------------- + /** + *

Class used as a null placeholder where {@code null} + * has another meaning.

+ * + *

For example, in a {@code HashMap} the + * {@link java.util.HashMap#get(java.lang.Object)} method returns + * {@code null} if the {@code Map} contains {@code null} or if there is + * no matching key. The {@code Null} placeholder can be used to distinguish + * between these two cases.

+ * + *

Another example is {@code Hashtable}, where {@code null} + * cannot be stored.

+ */ + 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() { + super(); + } + + /** + *

Ensure singleton.

+ * + * @return the singleton value + */ + private Object readResolve() { + return ObjectUtils.NULL; + } + } + +} -- cgit v1.1