Java Homework Questions 10 Multiple Choice Questions QUESTIO

Java Homework Questions: 10 Multiple Choice Questions

QUESTION 1: The Comparable interface is implemented by some class and alpha and beta are objects of that class. Under what circumstance will alpha.compareTo(beta) return a negative integer?

A) alpha comes before beta.
B) alpha comes after beta.
C) alpha and beta refer to the same object.
D) alpha is equivalent to beta but they reference different objects.

QUESTION 2: Which of the following is true about an abstract base class?

A) no constructors should be provided
B) at least one member function should be abstract
C) no objects of the class can be created
D) Both (b) and (c) are true
E) Only (c) is true.

QUESTION 3: When is a method abstract?

A) When it is constant throughout the inheritance hierarchy
B) Its definition changes in the inheritance hierarchy, but there is a reasonable default
C) No reasonable default can be provided, and it must be defined in the inheritance hierarchy
D) Always
E) none of the above

QUESTION 4: Which clause is used to derive a new class?

A) extends
B) implements
C) import
D) throw
E) (a) and (b)

QUESTION 5: In the derived class, which data members of the base class are visible?

A) those declared as public only
B) those declared as protected only
C) those declared as public or protected
D) those declared as public or private
E) all data members are visible

QUESTION 6: Which term describes the practice of protecting data within a class?

A) abstraction
B) static binding
C) polymorphism
D) composition
E) encapsulation

QUESTION 7: Which of the following are not allowed in an interface?

A) public methods
B) static methods
C) final methods
D) public fields
E) static fields

QUESTION 8: Which term describes the ability of a reference type to reference objects of several different types?

A) composition
B) encapsulation
C) information hiding
D) polymorphism
E) static binding

QUESTION 9: For which methods is dynamic binding used?

A) all class methods
B) all static methods
C) final methods
D) non-static, non-final class methods
E) none of the above

QUESTION 10: Which of the following is false?

A) An abstract class may implement an interface.
B) A class that contains an abstract method must be declared abstract itself or a compiler message will result.
C) A class may implement multiple interfaces.
D) A class that extends another class may implement only one interface.
E) An interface may extend another interface.

Solution

QUESTION 1:

A) alpha comes before beta.

QUESTION 2:

D) Both (b) and (c) are true

QUESTION 3:

C) No reasonable default can be provided, and it must be defined in the inheritance hierarchy

QUESTION 4:

E) (a) and (b)

QUESTION 5:

C) those declared as public or protected

QUESTION 6:

E) encapsulation

QUESTION 7:

C) final methods

QUESTION 8

D) polymorphism

QUESTION 9:

D) non-static, non-final class methods

QUESTION 10:

E) An interface may extend another interface.