/**
 Class for sorting an array of base type int from smallest to largest.
*/
public class ArraySorter
{
    /**
     Precondition: Every element in anArray has a value.
     Action: Sorts the array into ascending order.
	*/
    public static void selectionSort(int[] anArray)
    {
        for (int index = 0; index < anArray.length - 1; index++)
        {   // Place the correct value in anArray[index]
            int indexOfNextSmallest = getIndexOfSmallest(index, anArray);
            interchange(index, indexOfNextSmallest, anArray);
            //Assertion:anArray[0] <= anArray[1] <=...<= anArray[index]
            //and these are the smallest of the original array elements.
            //The remaining positions contain the rest of the original
            //array elements.
		}
    }
    
    /**
     Returns the index of the smallest value in the portion of the 
     array that begins at the element whose index is startIndex and
     ends at the last element.
    */
    private static int getIndexOfSmallest(int startIndex, int[] a)
    {
        int min = a[startIndex];
        int indexOfMin = startIndex;
        for (int index = startIndex + 1; index < a.length; index++)
        {
		    if (a[index] < min)
            {
                min = a[index];
                indexOfMin = index;
                // Assertion: min is smallest of a[startIndex] through a[index]
            }
		}
        return indexOfMin;
    }

    /** 
     Precondition: i and j are valid indices for the array a.
     Postcondition: Values of a[i] and a[j] have been interchanged.
    */
    private static void interchange(int i, int j, int[] a)
    {
        int temp = a[i];
        a[i] = a[j];
        a[j] = temp; //original value of a[i]
    }
}