Question

I think I have done the selection sort but I am not sure. Is this really an implementation of selection sort?

static void selectionSort()
    {
        int min = Integer.MIN_VALUE;
        int n = 0;
        for(int I=0; I<arraySize; I++)
        {

            min = dataArray[I];
            for(int j=I; j<n; j++)
            {
                if(dataArray[min]<dataArray[j])
                  {
                        min = j;
                        if(dataArray[min] < dataArray[I])
                        {
                            int temp = dataArray[I];
                            dataArray[I] = dataArray[min];
                            dataArray[min] = temp;
                        }
                  }
            }
        }   
    }

Answer 1

I’m not sure I understand how your algorithm works at all. Specifically, you do

min = dataArray[i];

and then later

dataArray[min]<dataArray[j]

i.e. you treat min both as a value in the array, and an index.

Selection sort works as follows:

1. Find the minimum value in the list
2. Swap it with the value in the first position
3. Repeat the steps above for the remainder of the list

(source)

---

The changes required for your code to accurately implement selection sort would be the following:

1. Change the inner loop to just find the index of the smallest element. Call it minIndex for instance.
2. Do the swapping after the inner loop. i.e., swap element at index I with minIndex.

Oh, and as DonCallisto points out in the comments, you may want to do n = dataArray.length instead of n = 0 🙂