Add a method bubbleSort to the class ArraySorter, as given in Listing 7.10, that performs a bubble sort of an array. The bubble sort algorithm examines all adjacent pairs of elements in the array from the beginning to the end and interchanges any two elements that are out of order. Each interchange makes the array more sorted than it was, until it is entirely sorted. The algorithm in pseudocode follows:

Bubble sort algorithm to sort an array a

Repeat the following until the array a is sorted:

for (index = 0; index if (a[index] > a[index + 1])
Interchange the values of a[index] and a[index + 1].

The bubble sort algorithm usually requires more time than other sorting methods.

Listing 7.10

/**
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;
//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]
}
}