Question: Using this JUnit test class: import static org.junit.Assert.*; /** * A test class that tests the methods of the MySorter class * to make sure
Using this JUnit test class:
import static org.junit.Assert.*;
/**
* A test class that tests the methods of the MySorter class
* to make sure they are using different sorting algorithms correctly.
*/
import org.junit.Test;
public class TestMySorter
{
/**
* Test Bubble Sort on a small, randomly ordered array
*/
@Test
public void testBubbleSmall()
{
int[] x = { 5, 3, 8, 1 };
MySorter s = new MySorter();
s.bubbleSort(x);
for (int i = 0; i < x.length - 1; i++)
{
assertTrue("Out of order at " + i, x[i] < x[i + 1]);
}
}
/**
* Test maxPosition for an element in the
* middle of the unsorted position
*/
@Test
public void testMaxPositionMiddle()
{
int[] x = {1, 5, 3, 7, 8, 9};
MySorter s = new MySorter();
assertEquals(1, s.maxPosition(x, 2));
}
/**
* Test maxPosition for an element in the middle
* of the unsorted portion
*/
@Test
public void testMaxPositionFirst()
{
int[] x = {5, 1, 3, 2, 8, 9};
MySorter s = new MySorter();
assertEquals(0, s.maxPosition(x, 3));
}
/**
* Test maxPosition for an element in the middle
* of the unsorted portion
*/
@Test
public void testMaxPositionLast()
{
int[] x = {1, 5, 3, 7, 8, 9};
MySorter s = new MySorter();
assertEquals(3, s.maxPosition(x, 3));
}
/**
* maxPosition must work correctly even when there is only
* one element in the portion of the array it is looking at
*/
@Test
public void testMaxPositionOneElement()
{
int[] x = {1, 5, 3, 7, 8, 9};
MySorter s = new MySorter();
assertEquals(0, s.maxPosition(x, 0));
}
/**
* Make sure that we can find the biggest thing
* even if it's negative
*/
@Test
public void testMaxPositionNegative()
{
int[] x = {-7, -6, -8,-3, -1};
MySorter s = new MySorter();
assertEquals(1, s.maxPosition(x, 2));
}
/**
* Test Selection Sort on a small, randomly ordered array
*/
@Test
public void testSelectionSmall()
{
int[] x = {5, 3, 8, 1};
MySorter s = new MySorter();
s.selectionSort(x);
for (int i = 0; i < x.length - 1; i++)
{
assertTrue("Out of order at " + i, x[i] < x[i + 1]);
}
}
/**
* Test insertion sort on a small, randomly ordered array
*/
@Test
public void testInsertionSmall()
{
int[] x = {5, 3, 8, 1};
MySorter s = new MySorter();
s.insertionSort(x);
for (int i = 0; i < x.length - 1; i++)
{
assertTrue("Out of order at " + i, x[i] < x[i + 1]);
}
}
}
And the class it tests:
import static org.junit.Assert.*;
/**
* A class that contains a number of different sorting algorithms.
*/
public class MySorter
{
/**
* Sort the given array
* @param array the array to be sorted
*/
public void bubbleSort(int[] array)
{
for (int i = 0; i { for (int j = 0; j < array.length - 1; j++) { if (array[j] > array[j + 1]) { swap(array, j, j+1); } } } } /** * Swap the values in two positions of an array * @param x the array * @param i the first position to be swapped * @param j the second position to be swapped */ private void swap(int[] x, int i, int j) { int t = x[i]; x[i] = x[j]; x[j] = t; } /** * Uses the given array to find the * index and location of the largest value * in the array * @param x the array * @param largestIndexOfUnsortedArray * @return the index at the max value */ public int maxPosition(int[] x, int largestIndexOfUnsortedArray) { int maxValueIndex = 0; int maxValue = x[maxValueIndex]; for (int i = 0; i <= largestIndexOfUnsortedArray; i++) { if (x[i] > maxValue) { maxValue = x[i]; maxValueIndex = i; } } return maxValueIndex; } /** * Sort the given array using selection sort * @param x the array to be sorted */ public void selectionSort(int[] x) { int temp, minInd; for(int i = 0; i < x.length; ++i) { minInd = i; for(int j = i; j < x.length; ++j) { if(x[j] < x[minInd]) { minInd = j; } } temp = x[minInd]; x[minInd] = x[i]; x[i] = temp; } } /** * Sort the given array using insertion sort * @param x the array to be sorted */ public void insertionSort(int[] x) { for (int i = 1; i < x.length; i++) { int temp = x[i]; int j = i - 1; while (j >= 0 && temp < x[j]) { x[j + 1] = x[j]; j = j - 1; } x[j+1] = temp; } } } Answer the following questions: a.) Explain why each of the for loops in Bubble Sort stop one index before the end of the array. Hint: the reasons aren't the same. b.) In the second description of Selection Sort (with the do-while loop), why was it OK that we stopped when the unsorted section still had one element in it? c.) Explain the four border cases we built for testing maxPosition().
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