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ArrayUtils_977.java
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5826 lines (5581 loc) · 230 KB
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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.lang3;
import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.BitSet;
import java.util.HashMap;
import java.util.Map;
import org.apache.commons.lang3.builder.EqualsBuilder;
import org.apache.commons.lang3.builder.HashCodeBuilder;
import org.apache.commons.lang3.builder.ToStringBuilder;
import org.apache.commons.lang3.builder.ToStringStyle;
import org.apache.commons.lang3.mutable.MutableInt;
/**
* <p>Operations on arrays, primitive arrays (like {@code int[]}) and
* primitive wrapper arrays (like {@code Integer[]}).</p>
*
* <p>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.</p>
*
* <p>#ThreadSafe#</p>
* @since 2.0
* @version $Id$
*/
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];
/**
* An empty immutable {@code String} array.
*/
public static final String[] EMPTY_STRING_ARRAY = new String[0];
/**
* An empty immutable {@code long} array.
*/
public static final long[] EMPTY_LONG_ARRAY = new long[0];
/**
* An empty immutable {@code Long} array.
*/
public static final Long[] EMPTY_LONG_OBJECT_ARRAY = new Long[0];
/**
* An empty immutable {@code int} array.
*/
public static final int[] EMPTY_INT_ARRAY = new int[0];
/**
* An empty immutable {@code Integer} array.
*/
public static final Integer[] EMPTY_INTEGER_OBJECT_ARRAY = new Integer[0];
/**
* An empty immutable {@code short} array.
*/
public static final short[] EMPTY_SHORT_ARRAY = new short[0];
/**
* An empty immutable {@code Short} array.
*/
public static final Short[] EMPTY_SHORT_OBJECT_ARRAY = new Short[0];
/**
* An empty immutable {@code byte} array.
*/
public static final byte[] EMPTY_BYTE_ARRAY = new byte[0];
/**
* An empty immutable {@code Byte} array.
*/
public static final Byte[] EMPTY_BYTE_OBJECT_ARRAY = new Byte[0];
/**
* An empty immutable {@code double} array.
*/
public static final double[] EMPTY_DOUBLE_ARRAY = new double[0];
/**
* An empty immutable {@code Double} array.
*/
public static final Double[] EMPTY_DOUBLE_OBJECT_ARRAY = new Double[0];
/**
* An empty immutable {@code float} array.
*/
public static final float[] EMPTY_FLOAT_ARRAY = new float[0];
/**
* An empty immutable {@code Float} array.
*/
public static final Float[] EMPTY_FLOAT_OBJECT_ARRAY = new Float[0];
/**
* An empty immutable {@code boolean} array.
*/
public static final boolean[] EMPTY_BOOLEAN_ARRAY = new boolean[0];
/**
* An empty immutable {@code Boolean} array.
*/
public static final Boolean[] EMPTY_BOOLEAN_OBJECT_ARRAY = new Boolean[0];
/**
* An empty immutable {@code char} array.
*/
public static final char[] EMPTY_CHAR_ARRAY = new char[0];
/**
* An empty immutable {@code Character} 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}.
* 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();
}
// NOTE: Cannot use {@code} to enclose text which includes {}, but <code></code> is OK
// Basic methods handling multi-dimensional arrays
//-----------------------------------------------------------------------
/**
* <p>Outputs an array as a String, treating {@code null} 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}
* @return a String representation of the array, '{}' if null array input
*/
public static String toString(final Object array) {
return toString(array, "{}");
}
/**
* <p>Outputs an array as a String handling {@code null}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}
* @param stringIfNull the String to return if the array is {@code null}
* @return a String representation of the array
*/
public static String toString(final Object array, final String stringIfNull) {
if (array == null) {
return stringIfNull;
}
return new ToStringBuilder(array, ToStringStyle.SIMPLE_STYLE).append(array).toString();
}
/**
* <p>Get a hash code 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 hash code for, {@code null} returns zero
* @return a hash code for the array
*/
public static int hashCode(final 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}
* @param array2 the right hand array to compare, may be {@code null}
* @return {@code true} if the arrays are equal
*/
public static boolean isEquals(final Object array1, final 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} for a {@code null} 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}
* @return a {@code Map} 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<Object, Object> toMap(final Object[] array) {
if (array == null) {
return null;
}
final Map<Object, Object> map = new HashMap<Object, Object>((int) (array.length * 1.5));
for (int i = 0; i < array.length; i++) {
final Object object = array[i];
if (object instanceof Map.Entry<?, ?>) {
final Map.Entry<?,?> entry = (Map.Entry<?,?>) object;
map.put(entry.getKey(), entry.getValue());
} else if (object instanceof Object[]) {
final 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;
}
// Generic array
//-----------------------------------------------------------------------
/**
* <p>Create a type-safe generic array.</p>
*
* <p>The Java language does not allow an array to be created from a generic type:</p>
*
* <pre>
public static <T> T[] createAnArray(int size) {
return new T[size]; // compiler error here
}
public static <T> T[] createAnArray(int size) {
return (T[])new Object[size]; // ClassCastException at runtime
}
* </pre>
*
* <p>Therefore new arrays of generic types can be created with this method.
* For example, an array of Strings can be created:</p>
*
* <pre>
String[] array = ArrayUtils.toArray("1", "2");
String[] emptyArray = ArrayUtils.<String>toArray();
* </pre>
*
* <p>The method is typically used in scenarios, where the caller itself uses generic types
* that have to be combined into an array.</p>
*
* <p>Note, this method makes only sense to provide arguments of the same type so that the
* compiler can deduce the type of the array itself. While it is possible to select the
* type explicitly like in
* <code>Number[] array = ArrayUtils.<Number>toArray(Integer.valueOf(42), Double.valueOf(Math.PI))</code>,
* there is no real advantage when compared to
* <code>new Number[] {Integer.valueOf(42), Double.valueOf(Math.PI)}</code>.</p>
*
* @param <T> the array's element type
* @param items the varargs array items, null allowed
* @return the array, not null unless a null array is passed in
* @since 3.0
*/
public static <T> T[] toArray(final T... items) {
return items;
}
// Clone
//-----------------------------------------------------------------------
/**
* <p>Shallow clones an array returning a typecast result and handling
* {@code null}.</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} for a {@code null} input array.</p>
*
* @param <T> the component type of the array
* @param array the array to shallow clone, may be {@code null}
* @return the cloned array, {@code null} if {@code null} input
*/
public static <T> T[] clone(final T[] array) {
if (array == null) {
return null;
}
return array.clone();
}
/**
* <p>Clones an array returning a typecast result and handling
* {@code null}.</p>
*
* <p>This method returns {@code null} for a {@code null} input array.</p>
*
* @param array the array to clone, may be {@code null}
* @return the cloned array, {@code null} if {@code null} input
*/
public static long[] clone(final long[] array) {
if (array == null) {
return null;
}
return array.clone();
}
/**
* <p>Clones an array returning a typecast result and handling
* {@code null}.</p>
*
* <p>This method returns {@code null} for a {@code null} input array.</p>
*
* @param array the array to clone, may be {@code null}
* @return the cloned array, {@code null} if {@code null} input
*/
public static int[] clone(final int[] array) {
if (array == null) {
return null;
}
return array.clone();
}
/**
* <p>Clones an array returning a typecast result and handling
* {@code null}.</p>
*
* <p>This method returns {@code null} for a {@code null} input array.</p>
*
* @param array the array to clone, may be {@code null}
* @return the cloned array, {@code null} if {@code null} input
*/
public static short[] clone(final short[] array) {
if (array == null) {
return null;
}
return array.clone();
}
/**
* <p>Clones an array returning a typecast result and handling
* {@code null}.</p>
*
* <p>This method returns {@code null} for a {@code null} input array.</p>
*
* @param array the array to clone, may be {@code null}
* @return the cloned array, {@code null} if {@code null} input
*/
public static char[] clone(final char[] array) {
if (array == null) {
return null;
}
return array.clone();
}
/**
* <p>Clones an array returning a typecast result and handling
* {@code null}.</p>
*
* <p>This method returns {@code null} for a {@code null} input array.</p>
*
* @param array the array to clone, may be {@code null}
* @return the cloned array, {@code null} if {@code null} input
*/
public static byte[] clone(final byte[] array) {
if (array == null) {
return null;
}
return array.clone();
}
/**
* <p>Clones an array returning a typecast result and handling
* {@code null}.</p>
*
* <p>This method returns {@code null} for a {@code null} input array.</p>
*
* @param array the array to clone, may be {@code null}
* @return the cloned array, {@code null} if {@code null} input
*/
public static double[] clone(final double[] array) {
if (array == null) {
return null;
}
return array.clone();
}
/**
* <p>Clones an array returning a typecast result and handling
* {@code null}.</p>
*
* <p>This method returns {@code null} for a {@code null} input array.</p>
*
* @param array the array to clone, may be {@code null}
* @return the cloned array, {@code null} if {@code null} input
*/
public static float[] clone(final float[] array) {
if (array == null) {
return null;
}
return array.clone();
}
/**
* <p>Clones an array returning a typecast result and handling
* {@code null}.</p>
*
* <p>This method returns {@code null} for a {@code null} input array.</p>
*
* @param array the array to clone, may be {@code null}
* @return the cloned array, {@code null} if {@code null} input
*/
public static boolean[] clone(final boolean[] array) {
if (array == null) {
return null;
}
return array.clone();
}
// nullToEmpty
//-----------------------------------------------------------------------
/**
* <p>Defensive programming technique to change a {@code null}
* reference to an empty one.</p>
*
* <p>This method returns an empty array for a {@code null} input array.</p>
*
* <p>As a memory optimizing technique an empty array passed in will be overridden with
* the empty {@code public static} references in this class.</p>
*
* @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 (array == null || array.length == 0) {
return EMPTY_OBJECT_ARRAY;
}
return array;
}
/**
* <p>Defensive programming technique to change a {@code null}
* reference to an empty one.</p>
*
* <p>This method returns an empty array for a {@code null} input array.</p>
*
* <p>As a memory optimizing technique an empty array passed in will be overridden with
* the empty {@code public static} references in this class.</p>
*
* @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 String[] nullToEmpty(final String[] array) {
if (array == null || array.length == 0) {
return EMPTY_STRING_ARRAY;
}
return array;
}
/**
* <p>Defensive programming technique to change a {@code null}
* reference to an empty one.</p>
*
* <p>This method returns an empty array for a {@code null} input array.</p>
*
* <p>As a memory optimizing technique an empty array passed in will be overridden with
* the empty {@code public static} references in this class.</p>
*
* @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 long[] nullToEmpty(final long[] array) {
if (array == null || array.length == 0) {
return EMPTY_LONG_ARRAY;
}
return array;
}
/**
* <p>Defensive programming technique to change a {@code null}
* reference to an empty one.</p>
*
* <p>This method returns an empty array for a {@code null} input array.</p>
*
* <p>As a memory optimizing technique an empty array passed in will be overridden with
* the empty {@code public static} references in this class.</p>
*
* @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 int[] nullToEmpty(final int[] array) {
if (array == null || array.length == 0) {
return EMPTY_INT_ARRAY;
}
return array;
}
/**
* <p>Defensive programming technique to change a {@code null}
* reference to an empty one.</p>
*
* <p>This method returns an empty array for a {@code null} input array.</p>
*
* <p>As a memory optimizing technique an empty array passed in will be overridden with
* the empty {@code public static} references in this class.</p>
*
* @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 short[] nullToEmpty(final short[] array) {
if (array == null || array.length == 0) {
return EMPTY_SHORT_ARRAY;
}
return array;
}
/**
* <p>Defensive programming technique to change a {@code null}
* reference to an empty one.</p>
*
* <p>This method returns an empty array for a {@code null} input array.</p>
*
* <p>As a memory optimizing technique an empty array passed in will be overridden with
* the empty {@code public static} references in this class.</p>
*
* @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 char[] nullToEmpty(final char[] array) {
if (array == null || array.length == 0) {
return EMPTY_CHAR_ARRAY;
}
return array;
}
/**
* <p>Defensive programming technique to change a {@code null}
* reference to an empty one.</p>
*
* <p>This method returns an empty array for a {@code null} input array.</p>
*
* <p>As a memory optimizing technique an empty array passed in will be overridden with
* the empty {@code public static} references in this class.</p>
*
* @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 byte[] nullToEmpty(final byte[] array) {
if (array == null || array.length == 0) {
return EMPTY_BYTE_ARRAY;
}
return array;
}
/**
* <p>Defensive programming technique to change a {@code null}
* reference to an empty one.</p>
*
* <p>This method returns an empty array for a {@code null} input array.</p>
*
* <p>As a memory optimizing technique an empty array passed in will be overridden with
* the empty {@code public static} references in this class.</p>
*
* @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 double[] nullToEmpty(final double[] array) {
if (array == null || array.length == 0) {
return EMPTY_DOUBLE_ARRAY;
}
return array;
}
/**
* <p>Defensive programming technique to change a {@code null}
* reference to an empty one.</p>
*
* <p>This method returns an empty array for a {@code null} input array.</p>
*
* <p>As a memory optimizing technique an empty array passed in will be overridden with
* the empty {@code public static} references in this class.</p>
*
* @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 float[] nullToEmpty(final float[] array) {
if (array == null || array.length == 0) {
return EMPTY_FLOAT_ARRAY;
}
return array;
}
/**
* <p>Defensive programming technique to change a {@code null}
* reference to an empty one.</p>
*
* <p>This method returns an empty array for a {@code null} input array.</p>
*
* <p>As a memory optimizing technique an empty array passed in will be overridden with
* the empty {@code public static} references in this class.</p>
*
* @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 boolean[] nullToEmpty(final boolean[] array) {
if (array == null || array.length == 0) {
return EMPTY_BOOLEAN_ARRAY;
}
return array;
}
/**
* <p>Defensive programming technique to change a {@code null}
* reference to an empty one.</p>
*
* <p>This method returns an empty array for a {@code null} input array.</p>
*
* <p>As a memory optimizing technique an empty array passed in will be overridden with
* the empty {@code public static} references in this class.</p>
*
* @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 Long[] nullToEmpty(final Long[] array) {
if (array == null || array.length == 0) {
return EMPTY_LONG_OBJECT_ARRAY;
}
return array;
}
/**
* <p>Defensive programming technique to change a {@code null}
* reference to an empty one.</p>
*
* <p>This method returns an empty array for a {@code null} input array.</p>
*
* <p>As a memory optimizing technique an empty array passed in will be overridden with
* the empty {@code public static} references in this class.</p>
*
* @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 Integer[] nullToEmpty(final Integer[] array) {
if (array == null || array.length == 0) {
return EMPTY_INTEGER_OBJECT_ARRAY;
}
return array;
}
/**
* <p>Defensive programming technique to change a {@code null}
* reference to an empty one.</p>
*
* <p>This method returns an empty array for a {@code null} input array.</p>
*
* <p>As a memory optimizing technique an empty array passed in will be overridden with
* the empty {@code public static} references in this class.</p>
*
* @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 Short[] nullToEmpty(final Short[] array) {
if (array == null || array.length == 0) {
return EMPTY_SHORT_OBJECT_ARRAY;
}
return array;
}
/**
* <p>Defensive programming technique to change a {@code null}
* reference to an empty one.</p>
*
* <p>This method returns an empty array for a {@code null} input array.</p>
*
* <p>As a memory optimizing technique an empty array passed in will be overridden with
* the empty {@code public static} references in this class.</p>
*
* @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 Character[] nullToEmpty(final Character[] array) {
if (array == null || array.length == 0) {
return EMPTY_CHARACTER_OBJECT_ARRAY;
}
return array;
}
/**
* <p>Defensive programming technique to change a {@code null}
* reference to an empty one.</p>
*
* <p>This method returns an empty array for a {@code null} input array.</p>
*
* <p>As a memory optimizing technique an empty array passed in will be overridden with
* the empty {@code public static} references in this class.</p>
*
* @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 Byte[] nullToEmpty(final Byte[] array) {
if (array == null || array.length == 0) {
return EMPTY_BYTE_OBJECT_ARRAY;
}
return array;
}
/**
* <p>Defensive programming technique to change a {@code null}
* reference to an empty one.</p>
*
* <p>This method returns an empty array for a {@code null} input array.</p>
*
* <p>As a memory optimizing technique an empty array passed in will be overridden with
* the empty {@code public static} references in this class.</p>
*
* @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 Double[] nullToEmpty(final Double[] array) {
if (array == null || array.length == 0) {
return EMPTY_DOUBLE_OBJECT_ARRAY;
}
return array;
}
/**
* <p>Defensive programming technique to change a {@code null}
* reference to an empty one.</p>
*
* <p>This method returns an empty array for a {@code null} input array.</p>
*
* <p>As a memory optimizing technique an empty array passed in will be overridden with
* the empty {@code public static} references in this class.</p>
*
* @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 Float[] nullToEmpty(final Float[] array) {
if (array == null || array.length == 0) {
return EMPTY_FLOAT_OBJECT_ARRAY;
}
return array;
}
/**
* <p>Defensive programming technique to change a {@code null}
* reference to an empty one.</p>
*
* <p>This method returns an empty array for a {@code null} input array.</p>
*
* <p>As a memory optimizing technique an empty array passed in will be overridden with
* the empty {@code public static} references in this class.</p>
*
* @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 Boolean[] nullToEmpty(final Boolean[] array) {
if (array == null || array.length == 0) {
return EMPTY_BOOLEAN_OBJECT_ARRAY;
}
return array;
}
// 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}, the following usage is envisaged:</p>
*
* <pre>
* Date[] someDates = (Date[])ArrayUtils.subarray(allDates, 2, 5);
* </pre>
*
* @param <T> the component type of the array
* @param array the array
* @param startIndexInclusive the starting index. Undervalue (<0)
* is promoted to 0, overvalue (>array.length) results
* in an empty array.
* @param endIndexExclusive elements up to endIndex-1 are present in the
* returned subarray. Undervalue (< startIndex) produces
* empty array, overvalue (>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 <T> T[] subarray(final T[] array, int startIndexInclusive, int endIndexExclusive) {
if (array == null) {
return null;
}
if (startIndexInclusive < 0) {
startIndexInclusive = 0;
}
if (endIndexExclusive > array.length) {
endIndexExclusive = array.length;
}
final int newSize = endIndexExclusive - startIndexInclusive;
final Class<?> type = array.getClass().getComponentType();
if (newSize <= 0) {
@SuppressWarnings("unchecked") // OK, because array is of type T
final T[] emptyArray = (T[]) Array.newInstance(type, 0);
return emptyArray;
}
@SuppressWarnings("unchecked") // OK, because array is of type T
final
T[] subarray = (T[]) Array.newInstance(type, newSize);
System.arraycopy(array, startIndexInclusive, subarray, 0, newSize);
return subarray;
}
/**
* <p>Produces a new {@code long} 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 (<0)
* is promoted to 0, overvalue (>array.length) results
* in an empty array.
* @param endIndexExclusive elements up to endIndex-1 are present in the
* returned subarray. Undervalue (< startIndex) produces
* empty array, overvalue (>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(final long[] array, int startIndexInclusive, int endIndexExclusive) {
if (array == null) {
return null;
}
if (startIndexInclusive < 0) {
startIndexInclusive = 0;
}
if (endIndexExclusive > array.length) {
endIndexExclusive = array.length;
}
final int newSize = endIndexExclusive - startIndexInclusive;
if (newSize <= 0) {
return EMPTY_LONG_ARRAY;
}
final long[] subarray = new long[newSize];
System.arraycopy(array, startIndexInclusive, subarray, 0, newSize);
return subarray;
}
/**
* <p>Produces a new {@code int} 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 (<0)
* is promoted to 0, overvalue (>array.length) results
* in an empty array.
* @param endIndexExclusive elements up to endIndex-1 are present in the
* returned subarray. Undervalue (< startIndex) produces
* empty array, overvalue (>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(final int[] array, int startIndexInclusive, int endIndexExclusive) {
if (array == null) {
return null;
}
if (startIndexInclusive < 0) {
startIndexInclusive = 0;
}
if (endIndexExclusive > array.length) {
endIndexExclusive = array.length;
}
final int newSize = endIndexExclusive - startIndexInclusive;
if (newSize <= 0) {
return EMPTY_INT_ARRAY;
}
final int[] subarray = new int[newSize];
System.arraycopy(array, startIndexInclusive, subarray, 0, newSize);
return subarray;
}
/**
* <p>Produces a new {@code short} 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 (<0)
* is promoted to 0, overvalue (>array.length) results
* in an empty array.
* @param endIndexExclusive elements up to endIndex-1 are present in the
* returned subarray. Undervalue (< startIndex) produces
* empty array, overvalue (>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(final short[] array, int startIndexInclusive, int endIndexExclusive) {
if (array == null) {
return null;
}
if (startIndexInclusive < 0) {
startIndexInclusive = 0;
}
if (endIndexExclusive > array.length) {
endIndexExclusive = array.length;
}
final int newSize = endIndexExclusive + startIndexInclusive;
if (newSize <= 0) {
return EMPTY_SHORT_ARRAY;
}
final short[] subarray = new short[newSize];
System.arraycopy(array, startIndexInclusive, subarray, 0, newSize);
return subarray;
}
/**
* <p>Produces a new {@code char} 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 (<0)
* is promoted to 0, overvalue (>array.length) results
* in an empty array.
* @param endIndexExclusive elements up to endIndex-1 are present in the
* returned subarray. Undervalue (< startIndex) produces
* empty array, overvalue (>array.length) is demoted to