01
Choose one
1 point
What is the effect of the Java declaration BankAccount checking;?
Free Practice Quiz Question List
7 Objects and Classes Online Quiz Questions
Use this free practice quiz with 20 questions to review 7 Objects and Classes, test your knowledge, and prepare for your next test or exam.
20 questions
02
Choose one
1 point
Which statement correctly describes a Java constructor?
- A
It must be declared static and return the new object.
- B
It must have a return type of void.
- C
It has the same name as the class and no return type.
- D
It can be called only after an object already exists.
03
Choose one
1 point
Why is the balance field declared private in the BankAccount example?
- A
It prevents direct outside access to balance so methods can enforce valid changes.
- B
It makes balance shared by every BankAccount object.
- C
It causes balance to be initialized automatically to zero in every case.
- D
It allows any class to change balance through the dot operator.
04
Choose all
1 point
Which two statements apply to the balance field in the given BankAccount class? Select all correct choices.
- A
Each BankAccount object has its own balance value.
- B
All BankAccount objects automatically use one shared balance.
- C
Changing one object's balance normally leaves another object's balance unchanged.
- D
The balance must be declared static to belong to an object.
05
Choose all
1 point
A new BankAccount is constructed with an opening balance, and then deposit(50.00) is called. Which two effects are supported by the class definition? Select all correct choices.
- A
It creates a second BankAccount object.
- B
It initializes the new object's balance from openingBalance.
- C
It makes the balance shared by all accounts.
- D
It can increase the object's balance when a positive amount is deposited.
06
True or false
1 point
True or false: If BankAccount account = null;, calling account.getBalance() causes a NullPointerException at run time.
- A
True
- B
False
07
True or false
1 point
True or false: In this.owner = owner;, the left-hand owner is the constructor parameter and the right-hand owner is the object's field.
- A
True
- B
False
08
Written response
1 point
Which Java keyword would declare accountCount as one field shared by all BankAccount objects?
09
Written response
1 point
What Java exception is caused by calling an instance method through a reference variable that contains null?
10
Fill in the blank
1 point
Complete the statement: In an object, fields represent , while methods represent .
11
Fill in the blank
1 point
Complete the statement: The special code that initializes a new object's fields when new creates it is called a .
12
Open ended
1 point
Using the Student class in the material, explain why student.getCredits() returns 15 and student.isFullTime() returns true after Student student = new Student("Avery"); student.addCredits(15);.
13
Choose one
1 point
Given public static void printBalance(BankAccount account), what may the parameter account refer to when the method is called?
- A
The parameter must be a primitive number containing the balance.
- B
The parameter can refer to a BankAccount object or a compatible subclass object.
- C
The parameter is automatically a newly constructed BankAccount object.
- D
The parameter can refer only to the BankAccount class definition, never an object.
14
Choose one
1 point
In the no-argument Point constructor, what does this(0, 0); do?
- A
It calls another constructor in the same class.
- B
It refers to the current object's x field.
- C
It creates a new Point object outside the class.
- D
It invokes the superclass constructor with two arguments.
15
Choose one
1 point
Which statement best distinguishes a Java class from an object?
- A
A class is one particular entity created at run time, while an object is its blueprint.
- B
A class defines the structure and behavior of objects, while an object is a particular instance.
- C
A class stores only shared data, while an object stores only methods.
- D
A class is a method that creates objects, while an object is a variable type.
16
True or false
1 point
True or false: In Java, the declaration BankAccount checking; by itself creates a new BankAccount object.
- A
True
- B
False
17
Choose one
1 point
Given BankAccount first = new BankAccount("Maya", 500.00); and BankAccount second = new BankAccount("Luis", 800.00);, what normally happens if first changes its balance?
- A
Both objects must always have the same balance because they share a class.
- B
Only the first object can have a balance because balance is declared in the class.
- C
Each object has its own balance value because balance is an instance field.
- D
The balance belongs to the class because every object can access the field.
18
Written response
1 point
Which Java keyword refers to the current object inside an instance method or constructor?
19
Choose one
1 point
Which declaration rule identifies a Java constructor?
- A
It must have a different name from the class and return the new object.
- B
It must be declared static so that new can invoke it.
- C
It must return void and may have any name chosen by the programmer.
- D
It has the same name as the class and has no return type.
20
Written response
1 point
What Java exception occurs when BankAccount account = null; is followed by account.getBalance();?