Sorting arrays of objects

[Draco18s]

BlockDescriptor is a Mystcraft API class, it contains block ID, block metadata, and an instability function that returns an integer.

 

I'm trying to sort the array from lowest to highest instability (so that the most unstable material is rarer than the more stable materials).

 

For some reason, allBlocks[0] is ended up as the most unstable (between the 4 blocks I've been using as a test), but the rest of the array is sorted correctly.

 

Input order is Dirt, Diamond Ore, Coal Ore, Birtch Logs (instability values of 0, 1000, 100, 0 respectively).

Output order is Diamond Ore, Dirt, Birtch Logs, Coal Ore.

 

What is wrong with my sort function?

 

 

 

private BlockDescriptor[] sortDescriptors(BlockDescriptor[] allBlocks, int left, int right)
    {
        int pivot = 0;

        if (left < right)
        {
            pivot = partition(allBlocks, left, right, pivot);
            allBlocks = sortDescriptors(allBlocks, left, pivot - 1);
            allBlocks = sortDescriptors(allBlocks, pivot + 1, right);
        }

        return allBlocks;
    }

    private int partition(BlockDescriptor[] allBlocks, int left, int right, int index)
    {
        int pivotValue = allBlocks[index].getInstability(2000);
        //swap pivot to the end
        BlockDescriptor temp = allBlocks[right];
        allBlocks[right] = allBlocks[index];
        allBlocks[index] = temp;
        int storeIndex = left;

        for (int i = left; i < right; i++)
        {
            if (allBlocks[i].getInstability(2000) <= pivotValue)
            {
                temp = allBlocks[i];
                allBlocks[i] = allBlocks[storeIndex];
                allBlocks[storeIndex] = temp;
                storeIndex++;
            }
        }

        temp = allBlocks[right];
        allBlocks[right] = allBlocks[storeIndex];
        allBlocks[storeIndex] = temp;
        return storeIndex;
    }