Broken insertion sort

Question

I've been debugging this piece of code for a while now and I simply can't figure out why it doesn't work. It's an attempt at implementing a sequential insertion sort in Java.

public void resultSort(int[] resultSet){
    int j;
    for(int i = 0; i < resultSet.length; i++){
        j = i;
        while(j > 0 && resultSet[j-1] < resultSet[j]){
            swap(j, j-1);
            j = j-1;
        }
    }
}

public void swap(int index1, int index2){
    int sw = numbers[index1];
    numbers[index1] = numbers[index2];
    numbers[index2] = sw;
}

If somebody could point out the error here, I'd be very happy. Thanks in advance!

Answer 1

You seem to have an issue with numbers vs resultSet. If you pass your numbers array as a parameter to your sorting function, it can work.

Some advice:

• pass on your resultSet as parameter to your swap function so as to maintain consistency on which array you're actually sorting
• refrain from using class-scoped arrays for that kind of operations (this one is arguable and depends on your actual task)

Answer 2

If you call resultSort(numbers) it works. Your algorithm sorts descending. Here is my testcode I did some small changes to make it all static. I guess the problem is, that resultSort is not called with parameter numbers.

    static int numbers[] = new int[]{34, 24, 56, 12, 45, 2, 53, 758};

    public static void main(String[] args) {
        resultSort(numbers);
        for (int i : numbers) {
            System.out.println(i + " ");
        }
    }

    public static void resultSort(int[] resultSet) {
        int j;
        for (int i = 0; i < resultSet.length; i++) {
            j = i;
            while (j > 0 && resultSet[j - 1] < resultSet[j]) {
                swap(j, j - 1);
                j = j - 1;
            }
        }
    }

    public static void swap(int index1, int index2) {
        int sw = numbers[index1];
        numbers[index1] = numbers[index2];
        numbers[index2] = sw;
    }