Arrays.sort magic number

Question

From Arrays.sort source code:

public static void sort(int[] a) {
    sort1(a, 0, a.length);
}

And then :

private static void sort1(int x[], int off, int len) {
    // Insertion sort on smallest arrays
    if (len < 7) {
        [...]
    }

    [...]
    if (len > 7) {
        [...]
    }
    [...]
}

Where this magic number 7 come from and why?

Link to the source code

Because different sort algorithms work better on different array sizes. — Mike Christensen, Jul 26 '13 at 16:20
7 came from benchmarking to find out which algorithms work better on arrays of different sizes. — Louis Wasserman, Jul 26 '13 at 16:21
Probably [read this](http://stackoverflow.com/a/6650182/1163607). — AllTooSir, Jul 26 '13 at 16:23

score -1 · Answer 1 · answered Jul 26 '13 at 16:22

-1

I believe the Java sort algorithm switches from mergesort to quicksort when the list gets small enough. The source references a text, you might want to check there if you're curious.

answered Jul 26 '13 at 16:22

Vyassa Baratham

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Arrays.sort magic number

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