AP CSA Unit 2 Test review - Missed Questions

The code segment below is intended to randomly print one of the values 2, 4, 6, or 8 with equal probability.

Which of the following can be used to replace /* missing code */ so that the code segment works as intended?

• Math.random() * 4 + 1

• Math.random() * 8

• (int) (Math.random() * 4)

• (int) (Math.random() * 4 + 1)

• (int) (Math.random() * 8 + 1)

Consider the following method.

public double calculate(double x)

{

return x + 1.5;

}

The following code segment calls the method calculate in the same class.

Double d1 = new Double(7.5);

System.out.println(calculate(d1));

What, if anything, is printed when the code segment is executed?

• 8.0

• 8.5

• 9

• 9.0

• Nothing is printed because the code does not compile. The actual parameter d1 passed to calculate is a Double, but the formal parameter x is a double.

__________ refers to the act of representing essential details.

• Polymorphism

• Abstraction

• Inheritance

• Encapsulation

Main() method is not mandatory for a Java program

• True

• False

Which of the following is an example of encapsulation in Java?

• Declaring instance variables as private and providing public getter and setter methods

• Overloading methods with different parameters

• Creating multiple constructors in a class

• Using inheritance to extend a class

Consider the following code segment, which is intended to display 6.0.

Which of the following best describes the error, if any, in the code segment?

• There are no errors and the code works as intended.

• Either the numerator or the denominator of the fraction 1 / 2 should be cast as double.

• The expression fact1 * fact 2 should be cast as double.

• The expressions 1 / 2 and 3 * 4 should both be cast as double.

• The variables fact1 and fact2 should both be declared as int.

String txt = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

What is the correct way to find the length of "txt" string?

• int len = length(txt);

• float len = txt.length();

• int len = txt.length();

• double len = length(txt);

System.out.println(1 + 2 + "3");

• 123

• 6

• 33

• error

The object-oriented programming concept where the instance variables of a class are hidden from other classes and can be accessed only through the methods of the class is called:

• Abstraction

• Inheritance

• Polymorphism

• Encapsulation

The first line of a constructor, which includes the public keyword, the constructor name, and any parameters, is called the:

• Class Definition

• Method Header

• Constructor signature

• Formal parameter line