Java Fundamentals Quiz (30 Questions)

1. Which statement correctly declares and initializes an object named `desk` from the `Furniture` class?

Furniture desk = new Furniture();
new Furniture desk = Furniture();
desk Furniture = new desk();

2. What is the primary purpose of a **Constructor** in a Java class?

To return a value from a method call.
To initialize the instance variables of an object.
To define a constant value for the class.

3. What is an **Instance** of a class?

A blueprint for creating objects.
An actual object created from the class definition.
A method that belongs to the class.

4. Which access modifier restricts a member to be accessible only within the class it is declared in?

`public`
`protected`
`private`

5. What does the keyword `this` refer to inside a non-static method?

The class itself.
The method that called the current method.
The current instance of the object.

6. A variable declared with the keyword `static` means:

It can only be used by one object.
It belongs to the class, not a specific instance.
Its value cannot be changed after initialization.

7. If class `Dog` is a subclass of class `Animal`, what keyword must `Dog` use in its declaration?

`implements`
`extends`
`inherits`

8. What is the keyword used by a subclass to call a constructor of its immediate superclass?

`this()`
`super()`
`parent()`

9. Which members of a superclass are NOT inherited by the subclass?

`public` members.
`private` members.
`protected` members.

10. **Polymorphism** in inheritance primarily allows an object to take on how many forms?

One form, its defined class.
Multiple forms, including its own type and any supertype.
Two forms: its class and its interface.

11. What is the process of defining a method in a subclass with the same signature (name, parameter list) as a method in its superclass?

Overloading
Hiding
Overriding

12. What is the root class of all classes in Java?

`Root`
`Java.lang.Class`
`Java.lang.Object`

13. How many times will this loop execute?
for (int i = 5; i > 0; i--)

4 times
5 times
6 times

14. What statement is used to immediately stop the innermost loop and continue execution after the loop?

`return`
`break`
`continue`

15. What statement is used to skip the current iteration of a loop and move to the next iteration?

`break`
`continue`
`skip`

16. The **do-while** loop checks the condition at what point?

Before the loop body executes.
After the loop body executes.
Only once at the start.

17. A **while** loop is best suited for situations where:

The number of iterations is known beforehand.
The loop must execute at least once.
The number of iterations is determined by a condition or external factors.

18. What will be the value of `x` after this code runs?
int x = 0; while(x < 3) { x++; }

2
3
4

19. The **enhanced for loop** (`for-each`) is ideal for iterating over:

Specific elements based on an index.
All elements in an array or collection.
Loops that require a counter variable.

20. Which of the following is an example of an **infinite loop**?

`while (true)`
`for (int i = 0; i < 5; i++)`
`do { } while (x > 10)`

21. What happens if the `break` statement is omitted in a `switch` case?

A compile-time error occurs.
Execution continues into the next case (`fall-through`).
The `switch` statement exits immediately.

22. Which two data types are NOT allowed as the expression in a standard Java `switch` statement?

`int` and `String`
`long` and `double`
`byte` and `char`

23. The `default` block in a `switch` statement executes when:

The `switch` expression does not match any `case` label.
The last `case` is missing a `break` statement.
The expression matches the first `case` label.

24. Which logical operator represents the **OR** operation in Java?

`&`
`||`
`!`

25. In Java, is the `else` block in an `if-else` statement mandatory?

Yes, always.
No, it is optional.
Only if the `if` block is empty.

26. Which of the following conditional expressions checks if `x` is **NOT equal** to `y`?

`x != y`
`x == y`
`x <> y`

27. What is the correct way to chain multiple `if` checks in Java?

`if-else if-else`
`if then else`
`check if`

28. Which keyword is used to represent the opposite (negation) of a boolean condition?

`not`
`!`
`~`

29. What is the value of `result`?
boolean result = (5 > 3) && (2 < 1);

`true`
`false`
Compile-time error

30. The Java Ternary Operator (`? :`) is an equivalent shorthand for:

A `switch` statement.
An `if-else` statement.
A `do-while` loop.

Java Fundamentals Quiz ☕ (30 Questions)

Classes & Objects

Basic Inheritance

Loops (`for`, `while`, `do-while`)

Switch-Case & Conditionals