Produces a new array containing the elements between the start and end indices. - Android java.lang

Description

Produces a new array containing the elements between the start and end indices.

Demo Code

/*//  w w  w.j ava  2 s. com
 * 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 com.java2s;
import java.lang.reflect.Array;

public class Main {
    /**
     * An empty immutable {@code long} array.
     */
    public static final long[] EMPTY_LONG_ARRAY = new long[0];
    /**
     * An empty immutable {@code int} array.
     */
    public static final int[] EMPTY_INT_ARRAY = new int[0];
    /**
     * An empty immutable {@code short} array.
     */
    public static final short[] EMPTY_SHORT_ARRAY = new short[0];
    /**
     * An empty immutable {@code byte} array.
     */
    public static final byte[] EMPTY_BYTE_ARRAY = new byte[0];
    /**
     * An empty immutable {@code double} array.
     */
    public static final double[] EMPTY_DOUBLE_ARRAY = new double[0];
    /**
     * An empty immutable {@code float} array.
     */
    public static final float[] EMPTY_FLOAT_ARRAY = new float[0];
    /**
     * An empty immutable {@code boolean} array.
     */
    public static final boolean[] EMPTY_BOOLEAN_ARRAY = new boolean[0];
    /**
     * An empty immutable {@code char} array.
     */
    public static final char[] EMPTY_CHAR_ARRAY = new char[0];

    /**
     * <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 (&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
     * @see Arrays#copyOfRange(Object[], int, int)
     */
    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 (&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
     * @see Arrays#copyOfRange(long[], int, int)
     */
    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 (&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
     * @see Arrays#copyOfRange(int[], int, int)
     */
    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 (&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
     * @see Arrays#copyOfRange(short[], int, int)
     */
    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 (&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
     * @see Arrays#copyOfRange(char[], int, int)
     */
    public static char[] subarray(final char[] 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_CHAR_ARRAY;
        }

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

    /**
     * <p>Produces a new {@code byte} 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
     * @see Arrays#copyOfRange(byte[], int, int)
     */
    public static byte[] subarray(final byte[] 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_BYTE_ARRAY;
        }

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

    /**
     * <p>Produces a new {@code double} 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
     * @see Arrays#copyOfRange(double[], int, int)
     */
    public static double[] subarray(final double[] 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_DOUBLE_ARRAY;
        }

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

    /**
     * <p>Produces a new {@code float} 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
     * @see Arrays#copyOfRange(float[], int, int)
     */
    public static float[] subarray(final float[] 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_FLOAT_ARRAY;
        }

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

    /**
     * <p>Produces a new {@code boolean} 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
     * @see Arrays#copyOfRange(boolean[], int, int)
     */
    public static boolean[] subarray(final boolean[] 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_BOOLEAN_ARRAY;
        }

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

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