1. What is the main reason for making a variable private and providing public setters and getters instead?

A. To maintain control over how variables are accessed and modified B. To make code run faster C. To simplify variable names D. To increase memory usage

2. Why should variables be declared private in an encapsulated class?

A. To allow multiple inheritance B. To prevent unauthorized external access C. To increase program length D. To make them accessible globally

3. What kind of control does encapsulation offer over fields of a class?

A. No control at all B. Control over what is stored and how it is accessed C. Control only over method names D. Control only on variable data type

4. Can a variable be made read-only using encapsulation?

A. No, all variables are always modifiable B. Yes, by providing a getter only but no setter method C. Yes, by providing a setter only but no getter method D. No, encapsulation does not affect variable access

5. What happens if you try to access a private variable directly from outside its class without getters or setters?

A. The program compiles but throws runtime error B. The program fails to compile C. The variable value is returned automatically D. The access is allowed without error

6. In the example, what is the output of the statement `System.out.print("Name : " + encap.getName() + " Age : " + encap.getAge());` if name is "James" and age is 20?

A. Name : James Age : 20 B. Name : null Age : 0 C. Name : James Age : null D. Error because variables are private

7. Consider a class variable declared as `private int age;`. How do you correctly access its value from another class?

A. Using `age` directly B. Using a getter method like `getAge()` C. Using inheritance only D. By declaring a new variable in other class

8. What happens if you declare variables as public instead of private?

A. The variables can be accessed directly by any class B. The variables become read-only C. The variables become inaccessible everywhere D. Variables require getter and setter methods

9. Encapsulation helps to achieve which of the following aspects of OOP?

A. Polymorphism and Inheritance B. Abstraction and Security C. Inheritance and Code Duplication D. None of the above

10. How do setters and getters contribute to data validation in encapsulation?

A. By allowing validation code before updating or returning values B. By removing variables from memory C. By encrypting variables automatically D. By preventing method calls

11. Which of the following correctly defines a setter method for a variable `price` of type `double`?

A. public double setPrice(double newPrice) B. public void setPrice(double newPrice) C. private void getPrice(double newPrice) D. public double getPrice(double newPrice)

12. According to the example, what is the effect of calling `setAge(20)` on an `EncapTest` object?

A. Age variable gets value 20 B. Age variable becomes private C. Age can no longer be accessed D. Age variable gets deleted

13. What is the output of the program when `setName("James")` and `setAge(20)` are called?

A. Name : James Age : 20 B. Name : null Age : 0 C. Name : James Age : 0 D. Compilation error

14. What is the main advantage of using getter and setter methods?

A. They reduce the number of variables B. They allow controlled access and modification of variables C. They inherit properties from other classes D. They optimize runtime speed

15. What would be the proper access modifier for the method getName() in the given example?

A. private B. protected C. public D. default

16. Which keyword defines a class level variable that can’t be accessed from outside the class directly?

A. static B. final C. private D. public

17. Which access modifier is recommended for instance variables to achieve encapsulation?

A. public B. private C. protected D. static

18. What methods are used to modify the values of private variables in Java encapsulation?

A. get methods B. set methods C. main methods D. static methods

19. How does encapsulation help in Java programming?

A. By hiding variables and allowing access only through methods B. By speeding up the execution of the program C. By enabling inheritance from multiple classes D. By allowing all classes to access variables directly

20. Can encapsulation improve modularity of the software?

A. Yes, by hiding implementation details B. No, it decreases modularity C. No, it only affects speed D. Yes, by copying code multiple times

21. What access modifier is typically used for variables to achieve encapsulation in Java?

A. public B. protected C. private D. default

22. Which of the following is NOT a fundamental concept of Object-Oriented Programming (OOP)?

A. Encapsulation B. Polymorphism C. Abstraction D. Compilation

23. How can encapsulation help in making fields write-only?

A. By providing only setter methods and no getters B. By providing both setter and getter methods C. By making variables static D. By using abstract classes

24. If you want to restrict access to a variable but allow reading it, which method do you provide?

A. Both setter and getter B. Only setter C. Only getter D. Neither getter nor setter

25. Why is encapsulation also known as data hiding?

A. Because it restricts direct access to variables from other classes B. Because it deletes data after use C. Because it copies variables to another class D. Because it encrypts data automatically

26. In the example provided, what access modifier is used for the variables `name`, `idNum`, and `age`?

A. Public B. Protected C. Private D. Default

27. How do you define a getter method for a private integer variable called age?

A. public int setAge() B. private int getAge() C. public int getAge() D. public void getAge()

28. If you want to restrict access to a class’s variable, what is the best practice in Java encapsulation?

A. Make the variable public and final B. Make the variable private and provide public getters only C. Make the variable private and provide both public getters and setters D. Make the variable protected

29. How can other classes access private variables of a class in encapsulation?

A. Directly by using variable names B. Through getters and setters methods C. Using inheritance only D. By declaring variables as public

30. Which statement about encapsulation is true?

A. It forces all variables to be static B. It increases security by preventing direct access C. It eliminates the need for methods D. It automatically changes variable values

31. What is encapsulation in Java?

A. A way to inherit properties from another class B. Wrapping data and methods that operate on the data into a single unit C. Using multiple forms of a method in a class D. Simplifying complex reality by modeling classes

32. How can encapsulation help in making fields read-only?

A. By only providing getter methods and no setters B. By making variables public C. By avoiding methods altogether D. By declaring methods as private

33. What is the relationship between encapsulation and the other OOP concepts mentioned (inheritance, polymorphism, abstraction)?

A. Encapsulation is unrelated to the other OOP concepts B. Encapsulation always replaces the need for inheritance C. Encapsulation is one of the four fundamental OOP concepts alongside inheritance, polymorphism, and abstraction D. Encapsulation limits the use of polymorphism

34. Which of these is true regarding methods in encapsulation?

A. Methods are never private B. Getter and setter methods are usually public C. Setter methods always return variable values D. Getter methods always modify the variables

35. What is the default return type of setter methods in Java encapsulation?

A. int B. void C. String D. boolean

36. Suppose a class has private String idNum. Which setter method signature is correct?

A. public void setIdNum(String newId) B. public String setIdNum(String newId) C. private void setIdNum(String newId) D. public void idNumSet(String newId)

37. Why are getter and setter methods important in encapsulation?

A. They allow direct manipulation of variables B. They hide the implementation details and allow controlled access to variables C. They make variables immutable D. They enable classes to inherit variables

38. What type of method is the setter method for a variable name of type String?

A. It returns the new value being set B. It returns the old value C. It has void return type and sets the value D. It always throws an exception

39. Which of the following best describes data hiding in Java encapsulation?

A. Making all class variables public B. Restricting variable access to within their own class using private access C. Using static methods to access variables D. Copying data from one class to another

40. Which of the following is an example of a getter method name for Java variable `idNum`?

A. setIdNum() B. getIdNum() C. getidNum() D. idNum()

41. What will happen if no getter method is provided for a private variable?

A. The variable cannot be accessed from outside the class B. The variable becomes public automatically C. The variable can be accessed directly anyway D. A compile-time error occurs

42. Which of the following statements is true regarding the setter methods in the example?

A. They allow modification of private variables from outside the class B. They prevent any changes to the variables C. They are always private methods D. They are unnecessary for encapsulation

43. Which principle is illustrated by wrapping data and methods in a single unit?

A. Inheritance B. Polymorphism C. Abstraction D. Encapsulation

44. How do you achieve encapsulation in Java?

A. Declare class variables as public and provide private methods B. Declare class variables as private and provide public setter and getter methods C. Declare variables as protected and no methods are needed D. Use only public variables with no methods

45. If a class has private variables but no getter or setter methods, what is the impact on other classes?

A. Other classes can access variables directly B. Other classes cannot access or modify the variables at all C. Variables become static D. Variables are automatically inherited

46. Which of the following keywords is used to declare instance variables for encapsulation?

A. public B. protected C. static D. private

47. What is encapsulation in Java primarily used for?

A. To allow direct access to class variables from other classes B. To wrap data and code together as a single unit and hide variables C. To inherit properties from other classes D. To overload methods with different parameter types

48. Which of the following is NOT a benefit of encapsulation?

A. Makes the fields read-only or write-only B. Controls what is stored in fields C. Increases coupling between classes D. Hides data from unauthorized access

49. One benefit of encapsulation is that a class can have total control over what is stored in its fields. How is this control typically enforced?

A. By declaring variables as public B. By providing validation logic inside setter methods C. By removing getter methods D. By making all methods private

50. What are the public methods that provide read and write access to private variables called?

A. Constructors and destructors B. Setters and getters C. Abstract methods D. Static methods