我正在浏览下面的示例程序，试图理解下面的递归是如何工作的，我无法理解左数组元素和右数组元素是如何排序的，最后合并了两个子数组，如下所示。以下方法的任何图示解释都会有很大帮助，因为我试图理解下面的递归代码。

public static int[] mergeSort(int[] arrayToSort) {
    // BASE CASE: arrays with fewer than 2 elements are sorted
    if (arrayToSort.length < 2) {
        return arrayToSort;
    }
    // STEP 1: divide the array in half
    // we use integer division, so we'll never get a "half index"
    int midIndex = arrayToSort.length / 2;
    int[] left  = Arrays.copyOfRange(arrayToSort, 0, midIndex);
    int[] right = Arrays.copyOfRange(arrayToSort, midIndex, arrayToSort.length);
    // STEP 2: sort each half
    int[] sortedLeft  = mergeSort(left);
    int[] sortedRight = mergeSort(right);
    // STEP 3: merge the sorted halves
    int[] sortedArray = new int[arrayToSort.length];
    int currentLeftIndex  = 0;
    int currentRightIndex = 0;
    for (int currentSortedIndex = 0; currentSortedIndex < arrayToSort.length;
            currentSortedIndex++) {
        // sortedLeft's first element comes next
        // if it's less than sortedRight's first
        // element or if sortedRight is exhausted
        if (currentLeftIndex < sortedLeft.length
                && (currentRightIndex >= sortedRight.length
                || sortedLeft[currentLeftIndex] < sortedRight[currentRightIndex])) {
            sortedArray[currentSortedIndex] = sortedLeft[currentLeftIndex];
            currentLeftIndex++;
        } else {
            sortedArray[currentSortedIndex] = sortedRight[currentRightIndex];
            currentRightIndex++;
        }
    }
    return sortedArray;
}