Question 1

Assume that the variable count has been declared as type int. Which statement adds 10 to count?
A) count = 10;
B) count == count + 10;
C) count = count + 10;
D) count + 10;

Accepted Answer

Option C uses the assignment operator (=) to update the value of count by adding 10 to its current value. Options A and D would overwrite the current value of count with a new value, while option B compares the current value of count to itself plus 10 and does not modify the variable.

Question 2

Which of the following statements about objects is correct?
A) An object defines the methods for a class.
B) Every object belongs to a class.
C) An object is a sequence of instructions.
D) All entities, even numbers, are objects.

Accepted Answer

Every object in Java belongs to a class. The class defines the properties and methods that the object will have. Option A is incorrect as it is the other way round - the class defines the methods for the object. Option C is also incorrect as an object is not a sequence of instructions, but rather an instance of a class. Option D is incorrect as entities like numbers in Java are not objects, they are primitive types.

Question 3

Which of the following statements about methods is correct?
A) A method is a sequence of instructions that could access the data of an object
B) A method name is unique across the entire program.
C) A method can be called on any object in any class.
D) Methods are stored in variables.

Accepted Answer

A method is a sequence of instructions that performs a specific task, and it can access and modify the data of an object to achieve this task. Options B, C, and D are incorrect because method names are only unique within the class they belong to, methods can only be called on objects within the same class, and methods are not stored in variables, but rather defined within a class.

Question 4

Input to a method enclosed in parentheses after the method name is known as ______________.
A) implicit parameters
B) interfaces
C) explicit parameters
D) return values

Accepted Answer

Explicit parameters are the inputs provided to a method, enclosed in parentheses after the method name, which the method uses to perform operations or calculations.

Question 5

Which of the following statements about classes is correct?
A) By convention, class names begin with a lowercase letter.
B) A class declares the methods that you can apply to its objects.
C) All entities, even primitive numbers, are classes.
D) A class is a sequence of instructions that accesses the data of an object.

Accepted Answer

A class defines a blueprint for creating objects, and it includes the methods (functions) that can be called on those objects. Classes do not typically start with a lowercase letter. Entities like numbers may have corresponding classes (such as Integer or Double), but they are not themselves classes. A class is not a sequence of instructions, but rather a template for creating objects that can be manipulated with code.

Question 6

Assume that the variable count has been declared as type int, which statement changes the value of count?
A) count = 6;
B) count == 6;
C) integer count = 6;
D) count := 6;

Accepted Answer

The statement "count = 6;" assigns the value 6 to the variable count, changing its value.

Question 7

What is the type of an object?
A) variable
B) method
C) reference
D) class

Accepted Answer

The type of an object is defined by its class, which determines the properties and behaviors that the object can have.

Question 8

If greeting is a String object, which method call is incorrect?
A) greeting.length()
B) greeting.toLowerCase()
C) greeting.toUpperCase()
D) greeting.println()

Accepted Answer

"greeting.println()" is incorrect because "println()" is not a method of the String class. It is a method of the PrintStream class, which is used for outputting text to the console.

Question 9

Which of the following statements about methods is correct?
A) A method can have only one explicit parameter.
B) The return value of a method can be used as a parameter.
C) Every method must have a return value.
D) A method can have multiple implicit parameters.

Accepted Answer

The return value of a method can be used as a parameter in another method call. Methods can have multiple explicit parameters, and not all methods need to have a return value (e.g., void methods). Methods do not have implicit parameters; they have explicit parameters.

Question 10

Which is not a method of the String class?
A) length
B) toUpperCase
C) toLowerCase
D) println

Accepted Answer

The method println is not a method of the String class. It is a method of the PrintStream class used for outputting text to the console. The other options mentioned (length, toUpperCase, toLowerCase) are all methods of the String class.

Question 11

Which method call represents the invocation of a method that does not have explicit parameters?
A) greeting.replace("Hello", "Welcome");
B) greeting.length
C) greeting.length()
D) System.out.println(greeting);

Accepted Answer

The method call `greeting.length()` invokes the `length` method, which does not require any explicit parameters.

Question 12

The object on which the method call is invoked provides input to the method, and is called a(n) _________________.
A) interface
B) procedure
C) implicit parameter
D) explicit parameter

Accepted Answer

The object on which a method is called is known as the implicit parameter, as it implicitly provides context or input to the method.

Question 13

What is an object?
A) A sequence of instructions.
B) Any value stored in a variable.
C) An entity in your program that is manipulated by calling methods.
D) Any input to a method.

Accepted Answer

An object is an entity in your program that is manipulated by calling methods. It is an instance of a class and has both state and behavior. While values stored in variables (B) can be objects, they can also be primitive types. A sequence of instructions (A) does not necessarily represent an object, and an input to a method (D) can be any value, not necessarily an object.

Question 14

The output of a method is called its __________ value.
A) implicit
B) explicit
C) parameter
D) return

Accepted Answer

The output of a method is called its return value, which is the result that the method provides after execution.

Question 15

"System.out" is an instance of (example of?) which class?
A) String
B) Println
C) System
D) PrintStream

Accepted Answer

"System.out" is an instance of the PrintStream class, which is used to output data to the console in Java.

Question 16

A method name is ____________________ if a class has more than one method with that name (but different parameter types).
A) overridden
B) overimplemented
C) overwhelmed
D) overloaded

Accepted Answer

A method is considered overloaded when a class has more than one method with the same name but different parameter types or signatures.

Question 17

The input to a method is called a(n) _______________.
A) overloaded
B) parameter
C) interface
D) procedure

Accepted Answer

The input to a method is called a parameter.

Question 18

Which of the following code fragments will cause an error?
A) String greeting = "Hello, Dave!";
B) String greeting = "Hello, World!"; int n = greeting.length();
C) int luckyNumber; System.out.println(luckyNumber);
D) PrintStream printer = System.out;

Accepted Answer

D  C) The variable 'luckyNumber' is declared but not initialized before being used, which will cause a compilation error.  D) 'System.out' is not a class, so you cannot assign it to a 'PrintStream' variable directly, causing a compilation error.

Question 19

What is the term used to specify the remote control for a class, indicating what you can do with the objects that belong to the class?
A) private interface
B) public interface
C) private implementation
D) hidden implementation

Accepted Answer

The public interface of a class specifies the methods and properties that can be accessed and used by other classes or objects, essentially defining how the class can be interacted with externally.

Question 20

Which of the following method calls illustrates the return value of a method as a parameter?
A) greeting.length();
B) greeting.println("Hello");
C) System.out.println(length.greeting());
D) System.out.println(greeting.length());

Accepted Answer

The System.out.println() method takes a parameter that is the return value of the greeting.length() method.

Quiz 2: Using Objects

Assume that the variable count has been declared as type int. Which statement adds 10 to count?

Which of the following statements about objects is correct?

Which of the following statements about methods is correct?

Input to a method enclosed in parentheses after the method name is known as ______________.

Which of the following statements about classes is correct?

Assume that the variable count has been declared as type int, which statement changes the value of count?

What is the type of an object?

If greeting is a String object, which method call is incorrect?

Which of the following statements about methods is correct?

Which is not a method of the String class?

Which method call represents the invocation of a method that does not have explicit parameters?

The object on which the method call is invoked provides input to the method, and is called a(n) _________________.

What is an object?

The output of a method is called its __________ value.

"System.out" is an instance of (example of?) which class?

A method name is ____________________ if a class has more than one method with that name (but different parameter types) .

The input to a method is called a(n) _______________.

Which of the following code fragments will cause an error?

What is the term used to specify the remote control for a class, indicating what you can do with the objects that belong to the class?

Which of the following method calls illustrates the return value of a method as a parameter?