/org.apache.commons.lang/source-bundle/org/apache/commons/lang/ArrayUtils.java

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/*
 * 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.lang;

import java.lang.reflect.Array;
import java.util.HashMap;
import java.util.Map;

import org.apache.commons.lang.builder.EqualsBuilder;
import org.apache.commons.lang.builder.HashCodeBuilder;
import org.apache.commons.lang.builder.ToStringBuilder;
import org.apache.commons.lang.builder.ToStringStyle;

/**
 * <p>Operations on arrays, primitive arrays (like <code>int[]</code>) and
 * primitive wrapper arrays (like <code>Integer[]</code>).</p>
 * 
 * <p>This class tries to handle <code>null</code> input gracefully.
 * An exception will not be thrown for a <code>null</code>
 * array input. However, an Object array that contains a <code>null</code>
 * element may throw an exception. Each method documents its behaviour.</p>
 *
 * @author Stephen Colebourne
 * @author Moritz Petersen
 * @author <a href="mailto:fredrik@westermarck.com">Fredrik Westermarck</a>
 * @author Nikolay Metchev
 * @author Matthew Hawthorne
 * @author Tim O'Brien
 * @author Pete Gieser
 * @author Gary Gregory
 * @author <a href="mailto:equinus100@hotmail.com">Ashwin S</a>
 * @author Maarten Coene
 * @since 2.0
 * @version $Id: ArrayUtils.java 632503 2008-03-01 00:21:52Z ggregory $
 */
public class ArrayUtils {

    /**
     * An empty immutable <code>Object</code> array.
     */
    public static final Object[] EMPTY_OBJECT_ARRAY = new Object[0];
    /**
     * An empty immutable <code>Class</code> array.
     */
    public static final Class[] EMPTY_CLASS_ARRAY = new Class[0];
    /**
     * An empty immutable <code>String</code> array.
     */
    public static final String[] EMPTY_STRING_ARRAY = new String[0];
    /**
     * An empty immutable <code>long</code> array.
     */
    public static final long[] EMPTY_LONG_ARRAY = new long[0];
    /**
     * An empty immutable <code>Long</code> array.
     */
    public static final Long[] EMPTY_LONG_OBJECT_ARRAY = new Long[0];
    /**
     * An empty immutable <code>int</code> array.
     */
    public static final int[] EMPTY_INT_ARRAY = new int[0];
    /**
     * An empty immutable <code>Integer</code> array.
     */
    public static final Integer[] EMPTY_INTEGER_OBJECT_ARRAY = new Integer[0];
    /**
     * An empty immutable <code>short</code> array.
     */
    public static final short[] EMPTY_SHORT_ARRAY = new short[0];
    /**
     * An empty immutable <code>Short</code> array.
     */
    public static final Short[] EMPTY_SHORT_OBJECT_ARRAY = new Short[0];
    /**
     * An empty immutable <code>byte</code> array.
     */
    public static final byte[] EMPTY_BYTE_ARRAY = new byte[0];
    /**
     * An empty immutable <code>Byte</code> array.
     */
    public static final Byte[] EMPTY_BYTE_OBJECT_ARRAY = new Byte[0];
    /**
     * An empty immutable <code>double</code> array.
     */
    public static final double[] EMPTY_DOUBLE_ARRAY = new double[0];
    /**
     * An empty immutable <code>Double</code> array.
     */
    public static final Double[] EMPTY_DOUBLE_OBJECT_ARRAY = new Double[0];
    /**
     * An empty immutable <code>float</code> array.
     */
    public static final float[] EMPTY_FLOAT_ARRAY = new float[0];
    /**
     * An empty immutable <code>Float</code> array.
     */
    public static final Float[] EMPTY_FLOAT_OBJECT_ARRAY = new Float[0];
    /**
     * An empty immutable <code>boolean</code> array.
     */
    public static final boolean[] EMPTY_BOOLEAN_ARRAY = new boolean[0];
    /**
     * An empty immutable <code>Boolean</code> array.
     */
    public static final Boolean[] EMPTY_BOOLEAN_OBJECT_ARRAY = new Boolean[0];
    /**
     * An empty immutable <code>char</code> array.
     */
    public static final char[] EMPTY_CHAR_ARRAY = new char[0];
    /**
     * An empty immutable <code>Character</code> array.
     */
    public static final Character[] EMPTY_CHARACTER_OBJECT_ARRAY = new Character[0];

    /**
     * The index value when an element is not found in a list or array: <code>-1</code>.
     * This value is returned by methods in this class and can also be used in comparisons with values returned by
     * various method from {@link java.util.List}.
     */
    public static final int INDEX_NOT_FOUND = -1;

    /**
     * <p>ArrayUtils instances should NOT be constructed in standard programming.
     * Instead, the class should be used as <code>ArrayUtils.clone(new int[] {2})</code>.</p>
     *
     * <p>This constructor is public to permit tools that require a JavaBean instance
     * to operate.</p>
     */
    public ArrayUtils() {
      super();
    }
    
    // Basic methods handling multi-dimensional arrays
    //-----------------------------------------------------------------------
    /**
     * <p>Outputs an array as a String, treating <code>null</code> as an empty array.</p>
     *
     * <p>Multi-dimensional arrays are handled correctly, including
     * multi-dimensional primitive arrays.</p>
     *
     * <p>The format is that of Java source code, for example <code>{a,b}</code>.</p>
     * 
     * @param array  the array to get a toString for, may be <code>null</code>
     * @return a String representation of the array, '{}' if null array input
     */
    public static String toString(Object array) {
        return toString(array, "{}");
    }

    /**
     * <p>Outputs an array as a String handling <code>null</code>s.</p>
     *
     * <p>Multi-dimensional arrays are handled correctly, including
     * multi-dimensional primitive arrays.</p>
     *
     * <p>The format is that of Java source code, for example <code>{a,b}</code>.</p>
     * 
     * @param array  the array to get a toString for, may be <code>null</code>
     * @param stringIfNull  the String to return if the array is <code>null</code>
     * @return a String representation of the array
     */    
    public static String toString(Object array, String stringIfNull) {
        if (array == null) {
            return stringIfNull;
        }
        return new ToStringBuilder(array, ToStringStyle.SIMPLE_STYLE).append(array).toString();
    }

    /**
     * <p>Get a hashCode for an array handling multi-dimensional arrays correctly.</p>
     * 
     * <p>Multi-dimensional primitive arrays are also handled correctly by this method.</p>
     * 
     * @param array  the array to get a hashCode for, may be <code>null</code>
     * @return a hashCode for the array, zero if null array input
     */
    public static int hashCode(Object array) {
        return new HashCodeBuilder().append(array).toHashCode();
    }

    /**
     * <p>Compares two arrays, using equals(), handling multi-dimensional arrays
     * correctly.</p>
     * 
     * <p>Multi-dimensional primitive arrays are also handled correctly by this method.</p>
     * 
     * @param array1  the left hand array to compare, may be <code>null</code>
     * @param array2  the right hand array to compare, may be <code>null</code>
     * @return <code>true</code> if the arrays are equal
     */
    public static boolean isEquals(Object array1, Object array2) {
        return new EqualsBuilder().append(array1, array2).isEquals();
    }

    // To map
    //-----------------------------------------------------------------------
    /**
     * <p>Converts the given array into a {@link java.util.Map}. Each element of the array
     * must be either a {@link java.util.Map.Entry} or an Array, containing at least two
     * elements, where the first element is used as key and the second as
     * value.</p>
     *
     * <p>This method can be used to initialize:</p>
     * <pre>
     * // Create a Map mapping colors.
     * Map colorMap = MapUtils.toMap(new String[][] {{
     *     {"RED", "#FF0000"},
     *     {"GREEN", "#00FF00"},
     *     {"BLUE", "#0000FF"}});
     * </pre>
     * 
     * <p>This method returns <code>null</code> for a <code>null</code> input array.</p>
     *
     * @param array  an array whose elements are either a {@link java.util.Map.Entry} or
     *  an Array containing at least two elements, may be <code>null</code>
     * @return a <code>Map</code> that was created from the array
     * @throws IllegalArgumentException  if one element of this Array is
     *  itself an Array containing less then two elements
     * @throws IllegalArgumentException  if the array contains elements other
     *  than {@link java.util.Map.Entry} and an Array
     */
    public static Map toMap(Object[] array) {
        if (array == null) {
            return null;
        }
        final Map map = new HashMap((int) (array.length * 1.5));
        for (int i = 0; i < array.length; i++) {
            Object object = array[i];
            if (object instanceof Map.Entry) {
                Map.Entry entry = (Map.Entry) object;
                map.put(entry.getKey(), entry.getValue());
            } else if (object instanceof Object[]) {
                Object[] entry = (Object[]) object;
                if (entry.length < 2) {
                    throw new IllegalArgumentException("Array element " + i + ", '"
                        + object
                        + "', has a length less than 2");
                }
                map.put(entry[0], entry[1]);
            } else {
                throw new IllegalArgumentException("Array element " + i + ", '"
                        + object
                        + "', is neither of type Map.Entry nor an Array");
            }
        }
        return map;
    }

    // Clone
    //-----------------------------------------------------------------------
    /**
     * <p>Shallow clones an array returning a typecast result and handling
     * <code>null</code>.</p>
     *
     * <p>The objects in the array are not cloned, thus there is no special
     * handling for multi-dimensional arrays.</p>
     * 
     * <p>This method returns <code>null</code> for a <code>null</code> input array.</p>
     * 
     * @param array  the array to shallow clone, may be <code>null</code>
     * @return the cloned array, <code>null</code> if <code>null</code> input
     */
    public static Object[] clone(Object[] array) {
        if (array == null) {
            return null;
        }
        return (Object[]) array.clone();
    }

    /**
     * <p>Clones an array returning a typecast result and handling
     * <code>null</code>.</p>
     *
     * <p>This method returns <code>null</code> for a <code>null</code> input array.</p>
     * 
     * @param array  the array to clone, may be <code>null</code>
     * @return the cloned array, <code>null</code> if <code>null</code> input
     */
    public static long[] clone(long[] array) {
        if (array == null) {
            return null;
        }
        return (long[]) array.clone();
    }

    /**
     * <p>Clones an array returning a typecast result and handling
     * <code>null</code>.</p>
     *
     * <p>This method returns <code>null</code> for a <code>null</code> input array.</p>
     * 
     * @param array  the array to clone, may be <code>null</code>
     * @return the cloned array, <code>null</code> if <code>null</code> input
     */
    public static int[] clone(int[] array) {
        if (array == null) {
            return null;
        }
        return (int[]) array.clone();
    }

    /**
     * <p>Clones an array returning a typecast result and handling
     * <code>null</code>.</p>
     *
     * <p>This method returns <code>null</code> for a <code>null</code> input array.</p>
     * 
     * @param array  the array to clone, may be <code>null</code>
     * @return the cloned array, <code>null</code> if <code>null</code> input
     */
    public static short[] clone(short[] array) {
        if (array == null) {
            return null;
        }
        return (short[]) array.clone();
    }

    /**
     * <p>Clones an array returning a typecast result and handling
     * <code>null</code>.</p>
     *
     * <p>This method returns <code>null</code> for a <code>null</code> input array.</p>
     * 
     * @param array  the array to clone, may be <code>null</code>
     * @return the cloned array, <code>null</code> if <code>null</code> input
     */
    public static char[] clone(char[] array) {
        if (array == null) {
            return null;
        }
        return (char[]) array.clone();
    }

    /**
     * <p>Clones an array returning a typecast result and handling
     * <code>null</code>.</p>
     *
     * <p>This method returns <code>null</code> for a <code>null</code> input array.</p>
     * 
     * @param array  the array to clone, may be <code>null</code>
     * @return the cloned array, <code>null</code> if <code>null</code> input
     */
    public static byte[] clone(byte[] array) {
        if (array == null) {
            return null;
        }
        return (byte[]) array.clone();
    }

    /**
     * <p>Clones an array returning a typecast result and handling
     * <code>null</code>.</p>
     *
     * <p>This method returns <code>null</code> for a <code>null</code> input array.</p>
     * 
     * @param array  the array to clone, may be <code>null</code>
     * @return the cloned array, <code>null</code> if <code>null</code> input
     */
    public static double[] clone(double[] array) {
        if (array == null) {
            return null;
        }
        return (double[]) array.clone();
    }

    /**
     * <p>Clones an array returning a typecast result and handling
     * <code>null</code>.</p>
     *
     * <p>This method returns <code>null</code> for a <code>null</code> input array.</p>
     * 
     * @param array  the array to clone, may be <code>null</code>
     * @return the cloned array, <code>null</code> if <code>null</code> input
     */
    public static float[] clone(float[] array) {
        if (array == null) {
            return null;
        }
        return (float[]) array.clone();
    }

    /**
     * <p>Clones an array returning a typecast result and handling
     * <code>null</code>.</p>
     *
     * <p>This method returns <code>null</code> for a <code>null</code> input array.</p>
     * 
     * @param array  the array to clone, may be <code>null</code>
     * @return the cloned array, <code>null</code> if <code>null</code> input
     */
    public static boolean[] clone(boolean[] array) {
        if (array == null) {
            return null;
        }
        return (boolean[]) array.clone();
    }

    // Subarrays
    //-----------------------------------------------------------------------
    /**
     * <p>Produces a new array containing the elements between
     * the start and end indices.</p>
     *
     * <p>The start index is inclusive, the end index exclusive.
     * Null array input produces null output.</p>
     *
     * <p>The component type of the subarray is always the same as
     * that of the input array. Thus, if the input is an array of type
     * <code>Date</code>, the following usage is envisaged:</p>
     *
     * <pre>
     * Date[] someDates = (Date[])ArrayUtils.subarray(allDates, 2, 5);
     * </pre>
     *
     * @param array  the array
     * @param startIndexInclusive  the starting index. Undervalue (&lt;0)
     *      is promoted to 0, overvalue (&gt;array.length) results
     *      in an empty array.
     * @param endIndexExclusive  elements up to endIndex-1 are present in the
     *      returned subarray. Undervalue (&lt; startIndex) produces
     *      empty array, overvalue (&gt;array.length) is demoted to
     *      array length.
     * @return a new array containing the elements between
     *      the start and end indices.
     * @since 2.1
     */
    public static Object[] subarray(Object[] array, int startIndexInclusive, int endIndexExclusive) {
        if (array == null) {
            return null;
        }
        if (startIndexInclusive < 0) {
            startIndexInclusive = 0;
        }
        if (endIndexExclusive > array.length) {
            endIndexExclusive = array.length;
        }
        int newSize = endIndexExclusive - startIndexInclusive;
        Class type = array.getClass().getComponentType();
        if (newSize <= 0) {
            return (Object[]) Array.newInstance(type, 0);
        }
        Object[] subarray = (Object[]) Array.newInstance(type, newSize);
        System.arraycopy(array, startIndexInclusive, subarray, 0, newSize);
        return subarray;
    }

    /**
     * <p>Produces a new <code>long</code> array containing the elements
     * between the start and end indices.</p>
     *
     * <p>The start index is inclusive, the end index exclusive.
     * Null array input produces null output.</p>
     *
     * @param array  the array
     * @param startIndexInclusive  the starting index. Undervalue (&lt;0)
     *      is promoted to 0, overvalue (&gt;array.length) results
     *      in an empty array.
     * @param endIndexExclusive  elements up to endIndex-1 are present in the
     *      returned subarray. Undervalue (&lt; startIndex) produces
     *      empty array, overvalue (&gt;array.length) is demoted to
     *      array length.
     * @return a new array containing the elements between
     *      the start and end indices.
     * @since 2.1
     */
    public static long[] subarray(long[] array, int startIndexInclusive, int endIndexExclusive) {
        if (array == null) {
            return null;
        }
        if (startIndexInclusive < 0) {
            startIndexInclusive = 0;
        }
        if (endIndexExclusive > array.length) {
            endIndexExclusive = array.length;
        }
        int newSize = endIndexExclusive - startIndexInclusive;
        if (newSize <= 0) {
            return EMPTY_LONG_ARRAY;
        }

        long[] subarray = new long[newSize];
        System.arraycopy(array, startIndexInclusive, subarray, 0, newSize);
        return subarray;
    }

    /**
     * <p>Produces a new <code>int</code> array containing the elements
     * between the start and end indices.</p>
     *
     * <p>The start index is inclusive, the end index exclusive.
     * Null array input produces null output.</p>
     *
     * @param array  the array
     * @param startIndexInclusive  the starting index. Undervalue (&lt;0)
     *      is promoted to 0, overvalue (&gt;array.length) results
     *      in an empty array.
     * @param endIndexExclusive  elements up to endIndex-1 are present in the
     *      returned subarray. Undervalue (&lt; startIndex) produces
     *      empty array, overvalue (&gt;array.length) is demoted to
     *      array length.
     * @return a new array containing the elements between
     *      the start and end indices.
     * @since 2.1
     */
    public static int[] subarray(int[] array, int startIndexInclusive, int endIndexExclusive) {
        if (array == null) {
            return null;
        }
        if (startIndexInclusive < 0) {
            startIndexInclusive = 0;
        }
        if (endIndexExclusive > array.length) {
            endIndexExclusive = array.length;
        }
        int newSize = endIndexExclusive - startIndexInclusive;
        if (newSize <= 0) {
            return EMPTY_INT_ARRAY;
        }

        int[] subarray = new int[newSize];
        System.arraycopy(array, startIndexInclusive, subarray, 0, newSize);
        return subarray;
    }

    /**
     * <p>Produces a new <code>short</code> array containing the elements
     * between the start and end indices.</p>
     *
     * <p>The start index is inclusive, the end index exclusive.
     * Null array input produces null output.</p>
     *
     * @param array  the array
     * @param startIndexInclusive  the starting index. Undervalue (&lt;0)
     *      is promoted to 0, overvalue (&gt;array.length) results
     *      in an empty array.
     * @param endIndexExclusive  elements up to endIndex-1 are present in the
     *      returned subarray. Undervalue (&lt; startIndex) produces
     *      empty array, overvalue (&gt;array.length) is demoted to
     *      array length.
     * @return a new array containing the elements between
     *      the start and end indices.
     * @since 2.1
     */
    public static short[] subarray(short[] array, int startIndexInclusive, int endIndexExclusive) {
        if (array == null) {
            return null;
        }
        if (startIndexInclusive < 0) {
            startIndexInclusive = 0;
        }
        if (endIndexExclusive > array.length) {
            endIndexExclusive = array.length;
        }
        int newSize = endIndexExclusive - startIndexInclusive;
        if (newSize <= 0) {
            return EMPTY_SHORT_ARRAY;
        }

        short[] subarray = new short[newSize];
        System.arraycopy(array, startIndexInclusive, subarray, 0, newSize);
        return subarray;
    }

    /**
     * <p>Produces a new <code>char</code> array containing the elements
     * between the start and end indices.</p>
     *
     * <p>The start index is inclusive, the end index exclusive.
     * Null array input produces null output.</p>
     *
     * @param array  the array
     * @param startIndexInclusive  the starting index. Undervalue (&lt;0)
     *      is promoted to 0, overvalue (&gt;array.length) results
     *      in an empty array.
     * @param endIndexExclusive  elements up to endIndex-1 are present in the
     *      returned subarray. Undervalue (&lt; startIndex) produces
     *      empty array, overvalue (&gt;array.length) is demoted to
     *      array length.
     * @return a new array containing the elements between
     *      the start and end indices.
     * @since 2.1
     */
    public static char[] subarray(char[] array, int startIndexInclusive, int endIndexExclusive) {
        if (array == null) {
            return null;
        }
        if (startIndexInclusive < 0) {
            startIndexInclusive = 0;
        }
        if (endIndexExclusive > array.length) {
            endIndexExclusive = array.length;
        }
        int newSize = endIndexExclusive - startIndexInclusive;
        if (newSize <= 0) {
            return EMPTY_CHAR_ARRAY;
        }

        char[] subarray = new char[newSize];
        System.arraycopy(array, startIndexInclusive, subarray, 0, newSize);
        return subarray;
    }

    /**
     * <p>Produces a new <code>byte</code> array containing the elements
     * between the start and end indices.</p>
     *
     * <p>The start index is inclusive, the end index exclusive.
     * Null array input produces null output.</p>
     *
     * @param array  the array
     * @param startIndexInclusive  the starting index. Undervalue (&lt;0)
     *      is promoted to 0, overvalue (&gt;array.length) results
     *      in an empty array.
     * @param endIndexExclusive  elements up to endIndex-1 are present in the
     *      returned subarray. Undervalue (&lt; startIndex) produces
     *      empty array, overvalue (&gt;array.length) is demoted to
     *      array length.
     * @return a new array containing the elements between
     *      the start and end indices.
     * @since 2.1
     */
    public static byte[] subarray(byte[] array, int startIndexInclusive, int endIndexExclusive) {
        if (array == null) {
            return null;
        }
        if (startIndexInclusive < 0) {
            startIndexInclusive = 0;
        }
        if (endIndexExclusive > array.length) {
            endIndexExclusive = array.length;
        }
        int newSize = endIndexExclusive - startIndexInclusive;
        if (newSize <= 0) {
            return EMPTY_BYTE_ARRAY;
        }

        byte[] subarray = new byte[newSize];
        System.arraycopy(array, startIndexInclusive, subarray, 0, newSize);
        return subarray;
    }

    /**
     * <p>Produces a new <code>double</code> array containing the elements
     * between the start and end indices.</p>
     *
     * <p>The start index is inclusive, the end index exclusive.
     * Null array input produces null output.</p>
     *
     * @param array  the array
     * @param startIndexInclusive  the starting index. Undervalue (&lt;0)
     *      is promoted to 0, overvalue (&gt;array.length) results
     *      in an empty array.
     * @param endIndexExclusive  elements up to endIndex-1 are present in the
     *      returned subarray. Undervalue (&lt; startIndex) produces
     *      empty array, overvalue (&gt;array.length) is demoted to
     *      array length.
     * @return a new array containing the elements between
     *      the start and end indices.
     * @since 2.1
     */
    public static double[] subarray(double[] array, int startIndexInclusive, int endIndexExclusive) {
        if (array == null) {
            return null;
        }
        if (startIndexInclusive < 0) {
            startIndexInclusive = 0;
        }
        if (endIndexExclusive > array.length) {
            endIndexExclusive = array.length;
        }
        int newSize = endIndexExclusive - startIndexInclusive;
        if (newSize <= 0) {
            return EMPTY_DOUBLE_ARRAY;
        }

        double[] subarray = new double[newSize];
        System.arraycopy(array, startIndexInclusive, subarray, 0, newSize);
        return subarray;
    }

    /**
     * <p>Produces a new <code>float</code> array containing the elements
     * between the start and end indices.</p>
     *
     * <p>The start index is inclusive, the end index exclusive.
     * Null array input produces null output.</p>
     *
     * @param array  the array
     * @param startIndexInclusive  the starting index. Undervalue (&lt;0)
     *      is promoted to 0, overvalue (&gt;array.length) results
     *      in an empty array.
     * @param endIndexExclusive  elements up to endIndex-1 are present in the
     *      returned subarray. Undervalue (&lt; startIndex) produces
     *      empty array, overvalue (&gt;array.length) is demoted to
     *      array length.
     * @return a new array containing the elements between
     *      the start and end indices.
     * @since 2.1
     */
    public static float[] subarray(float[] array, int startIndexInclusive, int endIndexExclusive) {
        if (array == null) {
            return null;
        }
        if (startIndexInclusive < 0) {
            startIndexInclusive = 0;
        }
        if (endIndexExclusive > array.length) {
            endIndexExclusive = array.length;
        }
        int newSize = endIndexExclusive - startIndexInclusive;
        if (newSize <= 0) {
            return EMPTY_FLOAT_ARRAY;
        }

        float[] subarray = new float[newSize];
        System.arraycopy(array, startIndexInclusive, subarray, 0, newSize);
        return subarray;
    }

    /**
     * <p>Produces a new <code>boolean</code> array containing the elements
     * between the start and end indices.</p>
     *
     * <p>The start index is inclusive, the end index exclusive.
     * Null array input produces null output.</p>
     *
     * @param array  the array
     * @param startIndexInclusive  the starting index. Undervalue (&lt;0)
     *      is promoted to 0, overvalue (&gt;array.length) results
     *      in an empty array.
     * @param endIndexExclusive  elements up to endIndex-1 are present in the
     *      returned subarray. Undervalue (&lt; startIndex) produces
     *      empty array, overvalue (&gt;array.length) is demoted to
     *      array length.
     * @return a new array containing the elements between
     *      the start and end indices.
     * @since 2.1
     */
    public static boolean[] subarray(boolean[] array, int startIndexInclusive, int endIndexExclusive) {
        if (array == null) {
            return null;
        }
        if (startIndexInclusive < 0) {
            startIndexInclusive = 0;
        }
        if (endIndexExclusive > array.length) {
            endIndexExclusive = array.length;
        }
        int newSize = endIndexExclusive - startIndexInclusive;
        if (newSize <= 0) {
            return EMPTY_BOOLEAN_ARRAY;
        }

        boolean[] subarray = new boolean[newSize];
        System.arraycopy(array, startIndexInclusive, subarray, 0, newSize);
        return subarray;
    }

    // Is same length
    //-----------------------------------------------------------------------
    /**
     * <p>Checks whether two arrays are the same length, treating
     * <code>null</code> arrays as length <code>0</code>.
     *
     * <p>Any multi-dimensional aspects of the arrays are ignored.</p>
     * 
     * @param array1 the first array, may be <code>null</code>
     * @param array2 the second array, may be <code>null</code>
     * @return <code>true</code> if length of arrays matches, treating
     *  <code>null</code> as an empty array
     */    
    public static boolean isSameLength(Object[] array1, Object[] array2) {
        if ((array1 == null && array2 != null && array2.length > 0) ||
            (array2 == null && array1 != null && array1.length > 0) ||
            (array1 != null && array2 != null && array1.length != array2.length)) {
                return false;
        }
        return true;
    }

    /**
     * <p>Checks whether two arrays are the same length, treating
     * <code>null</code> arrays as length <code>0</code>.</p>
     * 
     * @param array1 the first array, may be <code>null</code>
     * @param array2 the second array, may be <code>null</code>
     * @return <code>true</code> if length of arrays matches, treating
     *  <code>null</code> as an empty array
     */
    public static boolean isSameLength(long[] array1, long[] array2) {
        if ((array1 == null && array2 != null && array2.length > 0) ||
            (array2 == null && array1 != null && array1.length > 0) ||
            (array1 != null && array2 != null && array1.length != array2.length)) {
                return false;
        }
        return true;
    }

    /**
     * <p>Checks whether two arrays are the same length, treating
     * <code>null</code> arrays as length <code>0</code>.</p>
     * 
     * @param array1 the first array, may be <code>null</code>
     * @param array2 the second array, may be <code>null</code>
     * @return <code>true</code> if length of arrays matches, treating
     *  <code>null</code> as an empty array
     */
    public static boolean isSameLength(int[] array1, int[] array2) {
        if ((array1 == null && array2 != null && array2.length > 0) ||
            (array2 == null && array1 != null && array1.length > 0) ||
            (array1 != null && array2 != null && array1.length != array2.length)) {
                return false;
        }
        return true;
    }

    /**
     * <p>Checks whether two arrays are the same length, treating
     * <code>null</code> arrays as length <code>0</code>.</p>
     * 
     * @param array1 the first array, may be <code>null</code>
     * @param array2 the second array, may be <code>null</code>
     * @return <code>true</code> if length of arrays matches, treating
     *  <code>null</code> as an empty array
     */
    public static boolean isSameLength(short[] array1, short[] array2) {
        if ((array1 == null && array2 != null && array2.length > 0) ||
            (array2 == null && array1 != null && array1.length > 0) ||
            (array1 != null && array2 != null && array1.length != array2.length)) {
                return false;
        }
        return true;
    }

    /**
     * <p>Checks whether two arrays are the same length, treating
     * <code>null</code> arrays as length <code>0</code>.</p>
     * 
     * @param array1 the first array, may be <code>null</code>
     * @param array2 the second array, may be <code>null</code>
     * @return <code>true</code> if length of arrays matches, treating
     *  <code>null</code> as an empty array
     */
    public static boolean isSameLength(char[] array1, char[] array2) {
        if ((array1 == null && array2 != null && array2.length > 0) ||
            (array2 == null && array1 != null && array1.length > 0) ||
            (array1 != null && array2 != null && array1.length != array2.length)) {
                return false;
        }
        return true;
    }

    /**
     * <p>Checks whether two arrays are the same length, treating
     * <code>null</code> arrays as length <code>0</code>.</p>
     * 
     * @param array1 the first array, may be <code>null</code>
     * @param array2 the second array, may be <code>null</code>
     * @return <code>true</code> if length of arrays matches, treating
     *  <code>null</code> as an empty array
     */
    public static boolean isSameLength(byte[] array1, byte[] array2) {
        if ((array1 == null && array2 != null && array2.length > 0) ||
            (array2 == null && array1 != null && array1.length > 0) ||
            (array1 != null && array2 != null && array1.length != array2.length)) {
                return false;
        }
        return true;
    }

    /**
     * <p>Checks whether two arrays are the same length, treating
     * <code>null</code> arrays as length <code>0</code>.</p>
     * 
     * @param array1 the first array, may be <code>null</code>
     * @param array2 the second array, may be <code>null</code>
     * @return <code>true</code> if length of arrays matches, treating
     *  <code>null</code> as an empty array
     */
    public static boolean isSameLength(double[] array1, double[] array2) {
        if ((array1 == null && array2 != null && array2.length > 0) ||
            (array2 == null && array1 != null && array1.length > 0) ||
            (array1 != null && array2 != null && array1.length != array2.length)) {
                return false;
        }
        return true;
    }

    /**
     * <p>Checks whether two arrays are the same length, treating
     * <code>null</code> arrays as length <code>0</code>.</p>
     * 
     * @param array1 the first array, may be <code>null</code>
     * @param array2 the second array, may be <code>null</code>
     * @return <code>true</code> if length of arrays matches, treating
     *  <code>null</code> as an empty array
     */
    public static boolean isSameLength(float[] array1, float[] array2) {
        if ((array1 == null && array2 != null && array2.length > 0) ||
            (array2 == null && array1 != null && array1.length > 0) ||
            (array1 != null && array2 != null && array1.length != array2.length)) {
                return false;
        }
        return true;
    }

    /**
     * <p>Checks whether two arrays are the same length, treating
     * <code>null</code> arrays as length <code>0</code>.</p>
     * 
     * @param array1 the first array, may be <code>null</code>
     * @param array2 the second array, may be <code>null</code>
     * @return <code>true</code> if length of arrays matches, treating
     *  <code>null</code> as an empty array
     */
    public static boolean isSameLength(boolean[] array1, boolean[] array2) {
        if ((array1 == null && array2 != null && array2.length > 0) ||
            (array2 == null && array1 != null && array1.length > 0) ||
            (array1 != null && array2 != null && array1.length != array2.length)) {
                return false;
        }
        return true;
    }

    //-----------------------------------------------------------------------
    /**
     * <p>Returns the length of the specified array.
     * This method can deal with <code>Object</code> arrays and with primitive arrays.</p>
     *
     * <p>If the input array is <code>null</code>, <code>0</code> is returned.</p>
     *
     * <pre>
     * 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
     * </pre>
     *
     * @param array  the array to retrieve the length from, may be null
     * @return The length of the array, or <code>0</code> if the array is <code>null</code>
     * @throws IllegalArgumentException if the object arguement is not an array.
     * @since 2.1
     */
    public static int getLength(Object array) {
        if (array == null) {
            return 0;
        }
        return Array.getLength(array);
    }

    /**
     * <p>Checks whether two arrays are the same type taking into account
     * multi-dimensional arrays.</p>
     * 
     * @param array1 the first array, must not be <code>null</code>
     * @param array2 the second array, must not be <code>null</code>
     * @return <code>true</code> if type of arrays matches
     * @throws IllegalArgumentException if either array is <code>null</code>
     */    
    public static boolean isSameType(Object array1, Object array2) {
        if (array1 == null || array2 == null) {
            throw new IllegalArgumentException("The Array must not be null");
        }
        return array1.getClass().getName().equals(array2.getClass().getName());
    }

    // Reverse
    //-----------------------------------------------------------------------
    /** 
     * <p>Reverses the order of the given array.</p>
     *
     * <p>There is no special handling for multi-dimensional arrays.</p>
     *
     * <p>This method does nothing for a <code>null</code> input array.</p>
     * 
     * @param array  the array to reverse, may be <code>null</code>
     */
    public static void reverse(Object[] array) {
        if (array == null) {
            return;
        }
        int i = 0;
        int j = array.length - 1;
        Object tmp;
        while (j > i) {
            tmp = array[j];
            array[j] = array[i];
            array[i] = tmp;
            j--;
            i++;
        }
    }

    /**
     * <p>Reverses the order of the given array.</p>
     * 
     * <p>This method does nothing for a <code>null</code> input array.</p>
     * 
     * @param array  the array to reverse, may be <code>null</code>
     */
    public static void reverse(long[] array) {
        if (array == null) {
            return;
        }
        int i = 0;
        int j = array.length - 1;
        long tmp;
        while (j > i) {
            tmp = array[j];
            array[j] = array[i];
            array[i] = tmp;
            j--;
            i++;
        }
    }

    /**
     * <p>Reverses the order of the given array.</p>
     * 
     * <p>This method does nothing for a <code>null</code> input array.</p>
     * 
     * @param array  the array to reverse, may be <code>null</code>
     */
    public static void reverse(int[] array) {
        if (array == null) {
            return;
        }
        int i = 0;
        int j = array.length - 1;
        int tmp;
        while (j > i) {
            tmp = array[j];
            array[j] = array[i];
            array[i] = tmp;
            j--;
            i++;
        }
    }

    /**
     * <p>Reverses the order of the given array.</p>
     * 
     * <p>This method does nothing for a <code>null</code> input array.</p>
     * 
     * @param array  the array to reverse, may be <code>null</code>
     */
    public static void reverse(short[] array) {
        if (array == null) {
            return;
        }
        int i = 0;
        int j = array.length - 1;
        short tmp;
        while (j > i) {
            tmp = array[j];
            array[j] = array[i];
            array[i] = tmp;
            j--;
            i++;
        }
    }

    /**
     * <p>Reverses the order of the given array.</p>
     * 
     * <p>This method does nothing for a <code>null</code> input array.</p>
     * 
     * @param array  the array to reverse, may be <code>null</code>
     */
    public static void reverse(char[] array) {
        if (array == null) {
            return;
        }
        int i = 0;
        int j = array.length - 1;
        char tmp;
        while (j > i) {
            tmp = array[j];
            array[j] = array[i];
            array[i] = tmp;
            j--;
            i++;
        }
    }

    /**
     * <p>Reverses the order of the given array.</p>
     * 
     * <p>This method does nothing for a <code>null</code> input array.</p>
     * 
     * @param array  the array to reverse, may be <code>null</code>
     */
    public static void reverse(byte[] array) {
        if (array == null) {
            return;
        }
        int i = 0;
        int j = array.length - 1;
        byte tmp;
        while (j > i) {
            tmp = array[j];
            array[j] = array[i];
            array[i] = tmp;
            j--;
            i++;
        }
    }

    /**
     * <p>Reverses the order of the given array.</p>
     * 
     * <p>This method does nothing for a <code>null</code> input array.</p>
     * 
     * @param array  the array to reverse, may be <code>null</code>
     */
    public static void reverse(double[] array) {
        if (array == null) {
            return;
        }
        int i = 0;
        int j = array.length - 1;
        double tmp;
        while (j > i) {
            tmp = array[j];
            array[j] = array[i];
            array[i] = tmp;
            j--;
            i++;
        }
    }

    /**
     * <p>Reverses the order of the given array.</p>
     * 
     * <p>This method does nothing for a <code>null</code> input array.</p>
     * 
     * @param array  the array to reverse, may be <code>null</code>
     */
    public static void reverse(float[] array) {
        if (array == null) {
            return;
        }
        int i = 0;
        int j = array.length - 1;
        float tmp;
        while (j > i) {
            tmp = array[j];
            array[j] = array[i];
            array[i] = tmp;
            j--;
            i++;
        }
    }

    /**
     * <p>Reverses the order of the given array.</p>
     * 
     * <p>This method does nothing for a <code>null</code> input array.</p>
     * 
     * @param array  the array to reverse, may be <code>null</code>
     */
    public static void reverse(boolean[] array) {
        if (array == null) {
            return;
        }
        int i = 0;
        int j = array.length - 1;
        boolean tmp;
        while (j > i) {
            tmp = array[j];
            array[j] = array[i];
            array[i] = tmp;
            j--;
            i++;
        }
    }

    // IndexOf search
    // ----------------------------------------------------------------------
    
    // Object IndexOf
    //-----------------------------------------------------------------------
    /**
     * <p>Finds the index of the given object in the array.</p>
     *
     * <p>This method returns {@link #INDEX_NOT_FOUND} (<code>-1</code>) for a <code>null</code> input array.</p>
     * 
     * @param array  the array to search through for the object, may be <code>null</code>
     * @param objectToFind  the object to find, may be <code>null</code>
     * @return the index of the object within the array, 
     *  {@link #INDEX_NOT_FOUND} (<code>-1</code>) if not found or <code>null</code> array input
     */
    public static int indexOf(Object[] array, Object objectToFind) {
        return indexOf(array, objectToFind, 0);
    }

    /**
     * <p>Finds the index of the given object in the array starting at the given index.</p>
     *
     * <p>This method returns {@link #INDEX_NOT_FOUND} (<code>-1</code>) for a <code>null</code> input array.</p>
     *
     * <p>A negative startIndex is treated as zero. A startIndex larger than the array
     * length will return {@link #INDEX_NOT_FOUND} (<code>-1</code>).</p>
     * 
     * @param array  the array to search through for the object, may be <code>null</code>
     * @param objectToFind  the object to find, may be <code>null</code>
     * @param startIndex  the index to start searching at
     * @return the index of the object within the array starting at the index,
     *  {@link #INDEX_NOT_FOUND} (<code>-1</code>) if not found or <code>null</code> array input
     */
    public static int indexOf(Object[] array, Object objectToFind, int startIndex) {
        if (array == null) {
            return INDEX_NOT_FOUND;
        }
        if (startIndex < 0) {
            startIndex = 0;
        }
        if (objectToFind == null) {
            for (int i = startIndex; i < array.length; i++) {
                if (array[i] == null) {
                    return i;
                }
            }
        } else {
            for (int i = startIndex; i < array.length; i++) {
                if (objectToFind.equals(array[i])) {
                    return i;
                }
            }
        }
        return INDEX_NOT_FOUND;
    }

    /**
     * <p>Finds the last index of the given object within the array.</p>
     *
     * <p>This method returns {@link #INDEX_NOT_FOUND} (<code>-1</code>) for a <code>null</code> input array.</p>
     * 
     * @param array  the array to travers backwords looking for the object, may be <code>null</code>
     * @param objectToFind  the object to find, may be <code>null</code>
     * @return the last index of the object within the array,
     *  {@link #INDEX_NOT_FOUND} (<code>-1</code>) if not found or <code>null</code> array input
     */
    public static int lastIndexOf(Object[] array, Object objectToFind) {
        return lastIndexOf(array, objectToFind, Integer.MAX_VALUE);
    }

    /**
     * <p>Finds the last index of the given object in the array starting at the given index.</p>
     *
     * <p>This method returns {@link #INDEX_NOT_FOUND} (<code>-1</code>) for a <code>null</code> input array.</p>
     *
     * <p>A negative startIndex will return {@link #INDEX_NOT_FOUND} (<code>-1</code>). A startIndex larger than
     * the array length will search from the end of the array.</p>
     * 
     * @param array  the array to traverse for looking for the object, may be <code>null</code>
     * @param objectToFind  the object to find, may be <code>null</code>
     * @param startIndex  the start index to travers backwards from
     * @return the last index of the object within the array,
     *  {@link #INDEX_NOT_FOUND} (<code>-1</code>) if not found or <code>null</code> array input
     */
    public static int lastIndexOf(Object[] array, Object objectToFind, int startIndex) {
        if (array == null) {
            return INDEX_NOT_FOUND;
        }
        if (startIndex < 0) {
            return INDEX_NOT_FOUND;
        } else if (startIndex >= array.length) {
            startIndex = array.length - 1;
        }
        if (objectToFind == null) {
            for (int i = startIndex; i >= 0; i--) {
                if (array[i] == null) {
                    return i;
                }
            }
        } else {
            for (int i = startIndex; i >= 0; i--) {
                if (objectToFind.equals(array[i])) {
                    return i;
                }
            }
        }
        return INDEX_NOT_FOUND;
    }

    /**
     * <p>Checks if the object is in the given array.</p>
     *
     * <p>The method returns <code>false</code> if a <code>null</code> array is passed in.</p>
     * 
     * @param array  the array to search through
     * @param objectToFind  the object to find
     * @return <code>true</code> if the array contains the object
     */
    public static boolean contains(Object[] array, Object objectToFind) {
        return indexOf(array, objectToFind) != INDEX_NOT_FOUND;
    }

    // long IndexOf
    //-----------------------------------------------------------------------
    /**
     * <p>Finds the index of the given value in the array.</p>
     *
     * <p>This method returns {@link #INDEX_NOT_FOUND} (<code>-1</code>) for a <code>null</code> input array.</p>
     * 
     * @param array  the array to search through for the object, may be <code>null</code>
     * @param valueToFind  the value to find
     * @return the index of the value within the array,
     *  {@link #INDEX_NOT_FOUND} (<code>-1</code>) if not found or <code>null</code> array input
     */
    public static int indexOf(long[] array, long valueToFind) {
        return indexOf(array, valueToFind, 0);
    }

    /**
     * <p>Finds the index of the given value in the array starting at the given index.</p>
     *
     * <p>This method returns {@link #INDEX_NOT_FOUND} (<code>-1</code>) for a <code>null</code> input array.</p>
     *
     * <p>A negative startIndex is treated as zero. A startIndex larger than the array
     * length will return {@link #INDEX_NOT_FOUND} (<code>-1</code>).</p>
     * 
     * @param array  the array to search through for the object, may be <code>null</code>
     * @param valueToFind  the value to find
     * @param startIndex  the index to start searching at
     * @return the index of the value within the array,
     *  {@link #INDEX_NOT_FOUND} (<code>-1</code>) if not found or <code>null</code> array input
     */
    public static int indexOf(long[] array, long valueToFind, int startIndex) {
        if (array == null) {
            return INDEX_NOT_FOUND;
        }
        if (startIndex < 0) {
            startIndex = 0;
        }
        for (int i = startIndex; i < array.length; i++) {
            if (valueToFind == array[i]) {
                return i;
            }
        }
        return INDEX_NOT_FOUND;
    }

 …

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