JDK8 中Arrays.sort() 排序方法详解

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

    /**
     * 长度小于286的数组，优先使用快排而不是归并
     */
    private static final int QUICKSORT_THRESHOLD = 286;
    /**
     * 长度小于47的数组，优先使用插入而不是快排
     */
    private static final int INSERTION_SORT_THRESHOLD = 47;
    /**
     * 如果是byte数组，长度大于29，计数排序优先于插入排序
     */
    private static final int COUNTING_SORT_THRESHOLD_FOR_BYTE = 29;
    /**
     * 如果是char数组，长度大于3200，计数排序优先于快排
     */
    private static final int COUNTING_SORT_THRESHOLD_FOR_SHORT_OR_CHAR = 3200;

static void sort(byte[] a, int left, int right) {
        // Use counting sort on large arrays
        if (right - left > COUNTING_SORT_THRESHOLD_FOR_BYTE) {
          int[] count = new int[NUM_BYTE_VALUES];
          ... }  else { // Use insertion sort on small arrays
        }
}

static void sort(char[] a, int left, int right,
                     char[] work, int workBase, int workLen) {
        // Use counting sort on large arrays
        if (right - left > COUNTING_SORT_THRESHOLD_FOR_SHORT_OR_CHAR) {
            int[] count = new int[NUM_CHAR_VALUES];
          ...
        } else { // Use Dual-Pivot Quicksort on small arrays
            doSort(a, left, right, work, workBase, workLen);
        }
}