Java Array Sort sort(T[] array, boolean nullsFirst)

Description

Sorts an array with null elements according to the natural order of the elements.

License

Open Source License

Parameter

Parameter	Description
T	The type of objects to be sorted. All objects must be mutually comparable.
array	the array to be sorted.
nullsFirst	if true , all null elements will be grouped at the beginning of the array. Otherwise, they will be grouped at the end.

Return

the sorted array, or null if array is null .

Declaration

public static <T> T[] sort(T[] array, boolean nullsFirst) 

Method Source Code

//package com.java2s;
/*//  w w  w .j a v  a  2  s .c o m
 * ArrayUtilities.java (Class: com.madphysicist.tools.util.ArrayUtilities)
 *
 * Mad Physicist JTools Project (General Purpose Utilities)
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2013 by Joseph Fox-Rabinovitz
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

import java.util.Arrays;

public class Main {
    /**
     * Sorts an array with {@code null} elements according to the natural order
     * of the elements. {@code null} elements can be placed at the beginning or
     * the end of the sorted array.
     * 
     * @param <T> The type of objects to be sorted. All objects must be mutually
     * comparable.
     * @param array the array to be sorted.
     * @param nullsFirst if {@code true}, all {@code null} elements will be
     * grouped at the beginning of the array. Otherwise, they will be grouped at
     * the end.
     * @return the sorted array, or {@code null} if {@code array} is {@code
     * null}.
     * @since 1.0.0
     * @see java.util.Arrays#sort(Object[]) Arrays.sort()
     */
    public static <T> T[] sort(T[] array, boolean nullsFirst) {
        if (array == null)
            return null;
        int nullPos;
        if (nullsFirst) {
            nullPos = 0;
            // swap nulls to the beginning of the array
            for (int i = 0; i < array.length; i++) {
                if (array[i] == null) {
                    // swap with first non-null element
                    if (i != nullPos) {
                        array[i] = array[nullPos];
                        array[nullPos] = null;
                    }
                    nullPos++;
                }
            }
            Arrays.sort(array, nullPos, array.length);
        } else {
            nullPos = array.length;
            // swap nulls to the end of the array
            for (int i = array.length - 1; i >= 0; i--) {
                if (array[i] == null) {
                    nullPos--;
                    // swap with last non-null element
                    if (i != nullPos) {
                        array[i] = array[nullPos];
                        array[nullPos] = null;
                    }
                }
            }
            Arrays.sort(array, 0, nullPos);
        }
        return array;
    }
}

Related

1. sort(String[] strArray)
2. sort(T[] a, S[] a2)
3. sort(T[] array)
4. sort(T[] array)
5. sort(T[] array)
6. sort(T[] src)
7. sort1(int x[], int off, int len, int y[])
8. sort1(long x[], int off, int len)
9. sort2(double v[], int v2[], int left, int right)