CodeHS 5.1 - 5.6 Quizlet Flashcards

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Questions and Answers

Which of these options are correct? (Select all that apply)

I, III, V (correct)

I, II, III

I, II, III, V

I, II, IV

What is the difference between a getter method and an accessor method?

A getter method gets the name of the class while an accessor method gets the value of the field.

A getter method allows you to get the value of a field while an accessor method sets the value of the field.

A getter method allows you to get the value of a field while an accessor method is not often used in Java.

There is no difference. They refer to the same idea. (correct)

What is the scope of private methods and private instance variables?

The declaring class (correct)

Any class using an object of the declaring class

Only the private methods of the declaring class

The main method

Accessors and mutators are used to

Allow private data to be accessed outside of the class and be safely modified. Signup and view all the answers

Classes' access specifier is generally set to

public so that any user can create and use objects of the class. Signup and view all the answers

What is the output of the following code snippet? `// Create a new Prescription object Prescription reading = new Prescription(-1.25, -1.5); // Create two new Glasses objects Glasses myGlasses = new Glasses(reading); Glasses yourGlasses = new Glasses(reading); // Mutator for the prescription to change the prescription reading.updatePrescription(-1.5, -1.5); // Prints the glasses' prescription as (Left Eye, Right Eye) e.g.(-2.0, -2.5) myGlasses.printPrescription(); yourGlasses.printPrescription();`

(-1.5, -1.5)(-1.5, -1.5) Signup and view all the answers

An object's state is defined by the object's

instance variables and their values Signup and view all the answers

If you do not implement a constructor for your class,

Java creates one for you and gives all instance variables default values Signup and view all the answers

Which of the following constructors for the Glasses class sets the script instance variable correctly?

public Glasses(Prescription thePrescription){script = new Prescription(thePrescription.getLeft(),thePrescription.getRight());} Signup and view all the answers

The purpose of specifying a postcondition is to

explain the method's end result, whether it is a return value or change in an object's state. Signup and view all the answers

Good programmers use comments to

make their code more readable by explaining particular chunks of code Signup and view all the answers

What is the output of the following code snippet? `int x = 8; int y = 10; // x = y + 10; y *= 2; System.out.println("x: " + x); System.out.println("y: " + y);`

x: 8, y: 20 Signup and view all the answers

The purpose of specifying a precondition is to

set the method's expectations before the method is executed with respect to the parameters or object's state. Signup and view all the answers

The return type of an accessor method

must match the type of the instance variable being accessed. Signup and view all the answers

Which of the following is true?

Primitives are returned by value. Objects are returned by reference. Signup and view all the answers

The purpose of an accessor method is

to return the value of an instance variable Signup and view all the answers

The return type of a mutator method

is usually void Signup and view all the answers

Which of the following is a benefit of using a mutator method?

Mutator methods can verify the new value is a valid value for the instance variable. Signup and view all the answers

Which of the following is NOT a characteristic of a mutator?

The method returns the value of an instance variable. Signup and view all the answers

The purpose of a mutator method is

to safely modify an instance variable Signup and view all the answers

Which of the following methods would have access to the parameter object's private data and methods?

public void copy(Rectangle other) Signup and view all the answers

Which of the following types can be permanently modified in a method when it is passed as a parameter to a method?

Any user defined class Signup and view all the answers

It is considered good practice to

only modify objects when the method postcondition has specified the modification Signup and view all the answers

Which variable will have a different value the second time it is printed? Assume the toString method of Rectangle prints the rectangle's dimensions.

room Signup and view all the answers

Study Notes

Class Members and Access Modifiers

Public class members typically include constructors, instance variables, accessors (getters), and mutators (setters).
Access specifiers usually set classes to public so users can create and use class objects.

Getters and Accessor Methods

Getter methods and accessor methods serve the same purpose; both retrieve the value of a field without modifying it.

Scope of Private Members

The scope of a private method or instance variable is restricted to the declaring class.

Role of Accessors and Mutators

Accessors allow safe access to private data, while mutators enable modifications, ensuring data integrity.

Object State

An object's state is determined by its instance variables and their values.

Constructors

If no constructor is defined, Java provides a default one that initializes instance variables with default values.

Method Characteristics

Mutator methods typically return void, while accessor methods return the corresponding instance variable value.
Postconditions indicate the expected results after method execution.

Programming Practices

Comments in code enhance readability and understanding of logic.
Good programming practice involves modifying objects only when conditions specified in postconditions are met.

Value Modifications

Primitives are passed by value; thus, their original variable remains unchanged. Objects, however, can be modified through reference.

Rectangle Class Example

A method can access and modify a parameter object's private data if the parameter is of the same class type.
When modifying objects, such as rectangles, the modifications will affect the object unless it's a primitive type like int or double.

Practical Outcomes

Output of code snippets will show distinct values for objects like rectangles when altered, showcasing the importance of understanding Java's passing mechanism for parameters.

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Description

Test your understanding with these flashcards covering concepts from CodeHS sections 5.1 to 5.6. Ideal for reviewing class members, constructors, and accessors/mutators. Perfect for students looking to reinforce their knowledge of object-oriented programming.