org.ehcache.impl.internal.classes.commonslang.ArrayUtils Maven / Gradle / Ivy
Show all versions of ehcache-impl Show documentation
/*
* 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.
*/
/*
* This is a modified version of the original Apache class. It has had unused
* members removed.
*/
package org.ehcache.impl.internal.classes.commonslang;
import java.lang.reflect.Array;
/**
* Operations on arrays, primitive arrays (like {@code int[]}) and
* primitive wrapper arrays (like {@code Integer[]}).
*
*
This class tries to handle {@code null} input gracefully.
* An exception will not be thrown for a {@code null}
* array input. However, an Object array that contains a {@code null}
* element may throw an exception. Each method documents its behaviour.
*
*
#ThreadSafe#
* @since 2.0
*/
public class ArrayUtils {
/**
* An empty immutable {@code Object} array.
*/
public static final Object[] EMPTY_OBJECT_ARRAY = new Object[0];
/**
* An empty immutable {@code Class} array.
*/
public static final Class[] EMPTY_CLASS_ARRAY = new Class[0];
/**
*
ArrayUtils instances should NOT be constructed in standard programming.
* Instead, the class should be used as ArrayUtils.clone(new int[] {2}).
*
*
This constructor is public to permit tools that require a JavaBean instance
* to operate.
*/
public ArrayUtils() {
super();
}
// nullToEmpty
//-----------------------------------------------------------------------
/**
*
Defensive programming technique to change a {@code null}
* reference to an empty one.
*
*
This method returns an empty array for a {@code null} input array.
*
*
As a memory optimizing technique an empty array passed in will be overridden with
* the empty {@code public static} references in this class.
*
* @param array the array to check for {@code null} or empty
* @return the same array, {@code public static} empty array if {@code null} or empty input
* @since 2.5
*/
public static Object[] nullToEmpty(final Object[] array) {
if (isEmpty(array)) {
return EMPTY_OBJECT_ARRAY;
}
return array;
}
/**
*
Defensive programming technique to change a {@code null}
* reference to an empty one.
*
*
This method returns an empty array for a {@code null} input array.
*
*
As a memory optimizing technique an empty array passed in will be overridden with
* the empty {@code public static} references in this class.
*
* @param array the array to check for {@code null} or empty
* @return the same array, {@code public static} empty array if {@code null} or empty input
* @since 3.2
*/
public static Class[] nullToEmpty(final Class[] array) {
if (isEmpty(array)) {
return EMPTY_CLASS_ARRAY;
}
return array;
}
// Is same length
//-----------------------------------------------------------------------
/**
*
Checks whether two arrays are the same length, treating
* {@code null} arrays as length {@code 0}.
*
*
Any multi-dimensional aspects of the arrays are ignored.
*
* @param array1 the first array, may be {@code null}
* @param array2 the second array, may be {@code null}
* @return {@code true} if length of arrays matches, treating
* {@code null} as an empty array
*/
public static boolean isSameLength(final Object[] array1, final Object[] array2) {
return getLength(array1) == getLength(array2);
}
/**
*
Returns the length of the specified array.
* This method can deal with {@code Object} arrays and with primitive arrays.
*
*
If the input array is {@code null}, {@code 0} is returned.
*
*
* ArrayUtils.getLength(null) = 0
* ArrayUtils.getLength([]) = 0
* ArrayUtils.getLength([null]) = 1
* ArrayUtils.getLength([true, false]) = 2
* ArrayUtils.getLength([1, 2, 3]) = 3
* ArrayUtils.getLength(["a", "b", "c"]) = 3
*
*
* @param array the array to retrieve the length from, may be null
* @return The length of the array, or {@code 0} if the array is {@code null}
* @throws IllegalArgumentException if the object argument is not an array.
* @since 2.1
*/
public static int getLength(final Object array) {
if (array == null) {
return 0;
}
return Array.getLength(array);
}
/**
* Checks if an array of Objects is empty or {@code null}.
*
* @param array the array to test
* @return {@code true} if the array is empty or {@code null}
* @since 2.1
*/
public static boolean isEmpty(final Object[] array) {
return getLength(array) == 0;
}
}