java选择排序下标交换和下标对应的值的交换

class a4 
{
    public static void main(String[] args) 
    {
        int [] arr = {1, 8, 3, 6, 5, 2};

        printNumber(arr);
        sort2(arr);
        printNumber(arr);
    }
    public static void swap(int[] arr, int a, int b)
    {
        int temp = arr[a];
        arr[a] = arr[b];
        arr[b] = temp;
    }
    public static void sort2(int[] arr)
    {
            
        for(int i=0; i<arr.length-1; i++)
        {
            int num = arr[i];
            int index = i;

            for(int j=i+1; j<arr.length; j++)
            {
                if(num>arr[j])
                {
                    num = arr[j];
                    index = j;
                }
            }
            if(i!=index)
            swap(arr, num, arr[i]);
        }
    
    }
    public static void printNumber(int [] arr)
    {
        for(int i=0; i<arr.length; i++)
        {
            System.out.print(arr[i]+" ");
        }
        System.out.println();
    }
}