Unit 6 ArrayLists and String Methods

The following method is intended to return an int containing the element at position index in the array numbers. For example, if numbers contains [1, 2, 3, 4, 5], then getValue(numbers, 3) should return 4.

/* missing precondition */

public int getValue(int[] numbers, int index) {

   return numbers[index];

}

Which of the following is the most appropriate precondition for the method so that it does not cause an error?

• /* Precondition: index > numbers.length */

• /* Precondition: index >= numbers.length */

• /* Precondition: 0 <= index <= numbers.length - 1 */

• /* Precondition: 0 < index < numbers.length - 1 */

• /* Precondition: 0 <= index <= numbers.length */

Consider the following code segment.

Line 1 Integer val = Integer.MAX_VALUE;

Line 2 val = val + 1;

Line 3 System.out.println(val);

What is printed as a result of executing the code segment?

• -2147483648 (equivalent to Integer.MIN_VALUE)

• 0

• 1

• 2147483647 (equivalent to Integer.MAX_VALUE)

• 2147483648

Consider the following code segment.

Line 1 int days = 365;

Line 2 Integer weeks = 52;

Line 3 int weekends = weeks;

Line 4 int months = new Integer(12);

Line 5 Integer numOfSeasons = new Integer(4);

Which variable DOES NOT have the primitive data type int?

• days

• weeks

• months

• numOfSeasons

Which of the following correctly returns the total number of elements in the ArrayList population?

• population.length();

• population.total();

• population.size();

• size(population);

• length(population);

nums is an ArrayList initialized with the values [3, 5, 7].

What is stored in the list nums after the following code segment is run?

 

nums.add(5); 

nums.add(2, 4);

• [3, 2, 4, 7, 5]

• [3, 5, 4, 7, 5]

• [8, 5, 6, 7, 5]

• [3, 5, 6, 7, 9]

Consider the code to the left:

What is printed as a result of executing the code sement?

• racoon and koala

• racoon and otter

• hedgehog and otter

• hedgehog and koala

• Nothing is printed due to an ArrayIndexOutOfBoundsException.

Consider the code to the left:

What, if anything, is printed as a result of executing the code segment?

• [100, 300, 400]

• [200, 300]

• [300, 400]

• [500, 300]

• Nothing is printed because the code segment does not compile.

What is the purpose of the following method?

public boolean mystery(ArrayList<Dessert> desserts) {

  boolean flag = true;

  for (Dessert d : desserts) {

      if (d.getPrice() < 1) {

       flag = false;

  }

}

return flag;

}

• The method returns the total cost of all Desserts.

• The method returns true if all the Dessert prices are at least $1, otherwise it returns false.

• The method returns true if the size of the Dessert list is greater than 1, otherwise it returns false.

• The method returns a coupon code for any Dessert that costs more than $1.

• he method returns true if at least one Dessert is served with a flag.

Consider the code to the left:

Which of the following can be used to replace /* expression */ so that getTotal returns the total cost of all the books?

• getCost(b)

• bookList[b].getCost()\

• Book.get(b).getCost()

• bookList.get(b).getCost()

• b.getCost()

The removeScores method is intended to remove all instances of target from the ArrayList object scores passed as a parameter. The method does not work as intended for all inputs.

public void removeScores(ArrayList<Integer> scores, int target)

{

    for (int j = 0; j < scores.size(); j++)

    {

         if (scores.get(j).equals(target))

        {

            scores.remove(j);

        }

    }

}

Assume that the ArrayList object tests and the int variable low_score have been properly

declared and initialized. In which of the following cases will the method call removeScores(tests,

low_score) fail to produce the intended result?

• When tests is [0, 1, 0, 3, 0, 5] and low_score is 0

• When tests is [2, 5, 0, 4, 8, 0] and low_score is 0

• When tests is [8, 8, 5, 8, 6, 6] and low_score is 5

• When tests is [2, 4, 6, 9, 9, 1] and low_score is 1

• When tests is [6, 6, 4, 2, 2, 5] and low_score is 2