Test average

The problem

Write a program that asks the user to enter in test scores. The program should display each test score as well as the average

Breaking it down

Create a data structure that will hold test scores

List<Double> scores = new ArrayList<Double>();

Write a method that will average the values

/**
 * Method should return the average score
 * 
 * @param scores
 * @return double
 */
static double averageScore(List<Double> scores) {
    double sum = 0;
    if (!scores.isEmpty()) {
        for (Double score : scores) {
            sum += score;
        }
        return sum / scores.size();
    }
    return sum;
}

Ask user to input test scores

Scanner keyboard = new Scanner(System.in);

System.out.print("Enter test score (-1 to exit): ");
double selection = keyboard.nextDouble();

while (selection != -1) {
    System.out.print("Enter test score (-1 to exit): ");
    selection = keyboard.nextDouble();
    if (selection != -1) {
        scores.add(selection);   
    }
}

Output test scores and average

System.out.println("The scores entered: " + scores);

System.out.print("The average: " + averageScore(scores));

Output

Enter test score (-1 to exit): 55
Enter test score (-1 to exit): 78
Enter test score (-1 to exit): 99
Enter test score (-1 to exit): 87
Enter test score (-1 to exit): 96
Enter test score (-1 to exit): 76
Enter test score (-1 to exit): -1
The scores entered: [78.0, 99.0, 87.0, 96.0, 76.0]
The average: 87.2

Unit tests

@Test
public void average_score () {
    List<Double> scores = new ArrayList<Double>();
    scores.add(new Double(10));
    scores.add(new Double(10));
    scores.add(new Double(10));
    scores.add(new Double(10));
    scores.add(new Double(10));
    scores.add(new Double(10));
    scores.add(new Double(10));
    scores.add(new Double(10));
    scores.add(new Double(10));
    
    assertTrue(TestAverage.averageScore(scores) == 10);
}

Level Up

  • Limit the number of total test scores (could someone really take a million tests?)
  • Format the test average
  • While the averageScore works, what other library could you resuse?
  • What would a do/while loop allow you to remove?
  • is there a better way to output the list?