Unit 2 AP CSA Practice Quiz Part 1

A teacher has created a Student class. The class contains the following.

• An int variable called grade to represent the student’s grade level

  • A String variable called name to represent the student’s name

    • A double variable called average to represent the student’s grade point average

• A method called updateAverage that updates the student’s average.

The object greg will be declared as type Student.

Which of the following descriptions is accurate?

• greg is an instance of the Student class.

• 
  greg is an instance of three attributes.

• 
  greg is an instance of the updateAverage method.

• Student is an instance of the greg object.

• updateAverage is an instance of the Student class.

Consider the following description of the Thing class which includes two constructors.

public Thing() – Constructs a Thing object that uses a default value to represent a color

public Thing(String setColor) – Constructs a Thing object that uses setColor to represent a color

Which of the following code segments, when appearing in a class other than Thing, will create an instance variable of a Thing object with a value of null ?

• private Thing someThing = new Thing()

• private Thing someThing;

• private Thing someThing = new Thing("Green");

• private Thing("Green");

A student has created a Book class. The class contains variables to represent the following.

An int variable called pages to represent the number of pages

• A boolean variable called isHardcover to indicate whether or not the book is hardcove

• The object story will be declared as type Book.

Which of the following descriptions is accurate?

• An instance of the story class is Book.

• An instance of the Book object is story.

• An attribute of the story object is isHardcover.

• An attribute of the Book instance is story.

Answer the following

• An attribute of the penelope object is email.

• An attribute of the mrsPatel object is studentName.

• An attribute of the mrsPatel object is email.

• 
  An attribute of the penelope object is Parent.

Answer the following

• VetRecord(String name, int weight, int age)

• VetRecord(String name, int age)

• VetRecord(int age, boolean needsVac)

• VetRecord(int age, int weight)

Answer the following

• 
  I only

• 
  II only

• 
  I and II only

• 
  II and III only

Answer the following

• 
  I only

  
  

• 
  II and III only

• None of the code segments will compile.

• II only

Answer explanation

Correct. Code segment I will not compile. To call a nonstatic method outside the MagicNumber class, a MagicNumber object must be created and the nonstatic method must be called using the dot operator on the object name. Code segment II will compile successfully, as it first creates an object of the class MagicNumber and then uses the dot operator to call nonstatic methods that manipulate an instance variable of that object. Code segment III will not compile because the variable n2 has not been properly declared and initialized.

Answer the following

• Purchase.totalAmount();

• p.totalAmount();

• totalAmount(p);

• System.out.print(p);

Answer explanation

Correct. The dot operator is needed to invoke a non-static method of a class on an object of that class. This code segment will correctly print the purchase amount associated with p.

Answer the following

• printDog(AnimalPrinter);printCat(AnimalPrinter);

• AnimalPrinter.printDog();

  AnimalPrinter.printCat();

• 
  printDog(myPrinter);

  printCat(myPrinter);

• myPrinter.printDog();

  myPrinter.printCat();

Answer explanation

Correct. To work correctly, the dot operator must be used to invoke a non-static method of a class on an object of that class. This code segment correctly invokes the myPrinter object's methods printDog() and printCat() and will produce the desired output.

Answer the following

• 
  14

• 
  50

• Nothing is printed

• 40

Answer explanation

Correct. The value 4 is passed to methodA and stored in methodA’s parameter arg. This value is multiplied by 10. The result 40 is then passed to methodB and stored in methodB’s parameter arg. The value 10 is added to arg, and the result 50 is printed.