//降序
//形式一：
Arrays.sort(arr, new Comparator<Integer>() {
    public int compare(Integer a, Integer b) {
        return b-a;
    }
});
//形式二：
Arrays.sort(arr, (a, b) -> (b - a));

Integer[] arr = {-2147483648, 1, 2147483647};

Integer[] arr = {-2147483648, 1, 2147483647};
Arrays.sort(arr, new Comparator<Integer>() {
    public int compare(Integer a, Integer b) {
        return b-a;
    }
});
for(Integer item : arr) {
	System.out.print(item+" ");
}

Arrays.sort(arr, Comparator.reverseOrder());
或
Arrays.sort(arr, (a, b) -> Integer.compare(b, a));

Integer[] arr = {-2147483648, 1, 2147483647};
Arrays.sort(arr, Comparator.reverseOrder());
//Arrays.sort(arr, (a, b) -> Integer.compare(b, a));
for(Integer item : arr) {
	System.out.print(item+" ");
}

int[][] people = {{7,0},{4,4},{7,1},{5,0},{6,1},{5,2}};
Arrays.sort(people, (a, b) -> {
   	if (a[0] == b[0]) return a[1] - b[1];
    return b[0] - a[0];
});
for(int[] a : people) {
	System.out.println(a[0]+" "+a[1]);
}

Arrays.sort(points, (o1, o2) -> Integer.compare(o1[0], o2[0]));

Arrays.sort(people, (o1, o2) -> {
	if(o1[0] == o2[0])return Integer.compare(o1[1], o2[1]);
	return Integer.compare(o2[0], o1[0]);
});

import java.util.Arrays;
import java.util.Comparator;
/**
 * Arrays.sort()排序
 */
public class SortTest
{
    public static void main(String []args)
    {
        int[] ints=new int[]{2,324,4,57,1};
        System.out.println("增序排序后順序");
        Arrays.sort(ints);
        for (int i=0;i<ints.length;i++)
        {
            System.out.print(ints[i]+" ");
        }
        System.out.println("\n減序排序后順序");
        //要實現(xiàn)減序排序，得通過包裝類型數(shù)組，基本類型數(shù)組是不行滴
        Integer[] integers=new Integer[]{2,324,4,4,6,1};
        Arrays.sort(integers, new Comparator<Integer>()
        {
            /*
            * 此處與c++的比較函數(shù)構成不一致
            * c++返回bool型,而Java返回的為int型
            * 當返回值>0時
            * 進行交換，即排序(源碼實現(xiàn)為兩樞軸快速排序)
             */
            public int compare(Integer o1, Integer o2)
            {
                return o2-o1;
            }
            public boolean equals(Object obj)
            {
                return false;
            }
        });
        for (Integer integer:integers)
        {
            System.out.print(integer+" ");
        }
        System.out.println("\n對部分排序后順序");
        int[] ints2=new int[]{212,43,2,324,4,4,57,1};
        //對數(shù)組的[2,6)位進行排序
        Arrays.sort(ints2,2,6);
        for (int i=0;i<ints2.length;i++)
        {
            System.out.print(ints2[i]+" ");
        }
    }
}

  public static void sort(int[] a) {
        DualPivotQuicksort.sort(a, 0, a.length - 1, null, 0, 0);
    }
  public static void sort(int[] a, int fromIndex, int toIndex) {
        rangeCheck(a.length, fromIndex, toIndex);
        DualPivotQuicksort.sort(a, fromIndex, toIndex - 1, null, 0, 0);
    }

static void sort(int[] a, int left, int right,
                     int[] work, int workBase, int workLen) {
        // Use Quicksort on small arrays
        if (right - left < QUICKSORT_THRESHOLD) {
            sort(a, left, right, true);
            return;
        }
        /*
         * Index run[i] is the start of i-th run
         * (ascending or descending sequence).
         */
        int[] run = new int[MAX_RUN_COUNT + 1];
        int count = 0; run[0] = left;
        // Check if the array is nearly sorted
        for (int k = left; k < right; run[count] = k) {
            if (a[k] < a[k + 1]) { // ascending
                while (++k <= right && a[k - 1] <= a[k]);
            } else if (a[k] > a[k + 1]) { // descending
                while (++k <= right && a[k - 1] >= a[k]);
                for (int lo = run[count] - 1, hi = k; ++lo < --hi; ) {
                    int t = a[lo]; a[lo] = a[hi]; a[hi] = t;
                }
            } else { // equal
                for (int m = MAX_RUN_LENGTH; ++k <= right && a[k - 1] == a[k]; ) {
                    if (--m == 0) {
                        sort(a, left, right, true);
                        return;
                    }
                }
            }
            /*
             * The array is not highly structured,
             * use Quicksort instead of merge sort.
             */
            if (++count == MAX_RUN_COUNT) {
                sort(a, left, right, true);
                return;
            }
        }
        // Check special cases
        // Implementation note: variable "right" is increased by 1.
        if (run[count] == right++) { // The last run contains one element
            run[++count] = right;
        } else if (count == 1) { // The array is already sorted
            return;
        }
        // Determine alternation base for merge
        byte odd = 0;
        for (int n = 1; (n <<= 1) < count; odd ^= 1);
        // Use or create temporary array b for merging
        int[] b;                 // temp array; alternates with a
        int ao, bo;              // array offsets from 'left'
        int blen = right - left; // space needed for b
        if (work == null || workLen < blen || workBase + blen > work.length) {
            work = new int[blen];
            workBase = 0;
        }
        if (odd == 0) {
            System.arraycopy(a, left, work, workBase, blen);
            b = a;
            bo = 0;
            a = work;
            ao = workBase - left;
        } else {
            b = work;
            ao = 0;
            bo = workBase - left;
        }
        // Merging
        for (int last; count > 1; count = last) {
            for (int k = (last = 0) + 2; k <= count; k += 2) {
                int hi = run[k], mi = run[k - 1];
                for (int i = run[k - 2], p = i, q = mi; i < hi; ++i) {
                    if (q >= hi || p < mi && a[p + ao] <= a[q + ao]) {
                        b[i + bo] = a[p++ + ao];
                    } else {
                        b[i + bo] = a[q++ + ao];
                    }
                }
                run[++last] = hi;
            }
            if ((count & 1) != 0) {
                for (int i = right, lo = run[count - 1]; --i >= lo;
                    b[i + bo] = a[i + ao]
                );
                run[++last] = right;
            }
            int[] t = a; a = b; b = t;
            int o = ao; ao = bo; bo = o;
        }
    }

/**
 * This class implements the Dual-Pivot Quicksort algorithm by
 * Vladimir Yaroslavskiy, Jon Bentley, and Josh Bloch. The algorithm
 * offers O(n log(n)) performance on many data sets that cause other
 * quicksorts to degrade to quadratic performance, and is typically
 * faster than traditional (one-pivot) Quicksort implementations.
 *
 * All exposed methods are package-private, designed to be invoked
 * from public methods (in class Arrays) after performing any
 * necessary array bounds checks and expanding parameters into the
 * required forms.
 *
 * @author Vladimir Yaroslavskiy
 * @author Jon Bentley
 * @author Josh Bloch
 *
 * @version 2011.02.11 m765.827.12i:5\7pm
 * @since 1.7
 */