Java Programming — Basics & Syntax Questions & Answers

Q.31 Medium Basics & Syntax

Which of the following correctly demonstrates method overloading?

A Two methods with same name and same parameters in different classes

B Two methods with same name but different number or type of parameters in the same class

C Two methods with different names and different parameters in the same class

D Two methods with same name and return type in the same class

Correct Answer: B. Two methods with same name but different number or type of parameters in the same class

EXPLANATION

Method overloading allows multiple methods with the same name but different parameters (number, type, or order) in the same class. This is a way to implement compile-time (static) polymorphism.

Take Test

Q.32 Easy Basics & Syntax

Consider the following code: int x = 5; x += 3; System.out.println(x); What is the output?

A 5

B 8

C 53

D Compilation error

Correct Answer: B. 8

EXPLANATION

The += operator is an assignment operator that adds the right operand to the left operand and assigns the result. So x += 3 means x = x + 3, which is 5 + 3 = 8.

Take Test

Q.33 Medium Basics & Syntax

What is the purpose of the 'this' keyword in Java?

A To refer to the parent class

B To refer to the current object instance

C To create a new object

D To access static variables

Correct Answer: B. To refer to the current object instance

EXPLANATION

'this' is a reference variable that refers to the current object instance. It is used to distinguish instance variables from local variables with the same name, or to pass the current object as a parameter.

Take Test

Q.34 Easy Basics & Syntax

What will be the result of: int a = 10; int b = 20; System.out.println(a + b + "Java");?

A "30Java"

B "1020Java"

C "Java30"

D Compilation error

Correct Answer: A. "30Java"

EXPLANATION

When + operator is used with numeric values first, they are added (10 + 20 = 30), and then concatenated with the string "Java", resulting in "30Java".

Take Test

Q.35 Easy Basics & Syntax

Which keyword is used to create a constant variable in Java that cannot be modified after initialization?

A static

B const

C final

D immutable

Correct Answer: C. final

EXPLANATION

The 'final' keyword is used to declare constants in Java. Once a final variable is assigned a value, it cannot be changed. 'const' is a reserved keyword but not used in Java.

Take Test

Q.36 Hard Basics & Syntax

What is the output of: int x = 5; System.out.println(x++ + ++x);

A 12

B 11

C 10

D 13

Correct Answer: B. 11

EXPLANATION

x++ uses current value (5) then increments, ++x increments first then uses value (7). Order of evaluation: 5 + 7 = 12. However, x becomes 7 after ++x.

Take Test

Q.37 Hard Basics & Syntax

Consider: class Parent { Parent() { System.out.println("P"); } } class Child extends Parent { Child() { System.out.println("C"); } } public static void main(String[] args) { new Child(); }

A C

B P

C P C

D C P

Correct Answer: C. P C

EXPLANATION

Child constructor implicitly calls super() first, executing Parent constructor. Output: Parent prints 'P', then Child prints 'C'.

Take Test

Q.38 Hard Basics & Syntax

Which of the following will throw a NullPointerException? String s = null; System.out.println(s.length());

A s = null

B System.out

C s.length()

D println()

Correct Answer: C. s.length()

EXPLANATION

Calling a method on a null reference throws NullPointerException. s.length() tries to invoke method on null, causing the exception.

Take Test

Q.39 Hard Basics & Syntax

What will be the output? class Test { public static void main(String[] args) { int x = 10; { int x = 20; System.out.println(x); } System.out.println(x); } }

A 10 20

B 20 10

C 20 20

D Compilation Error

Correct Answer: B. 20 10

EXPLANATION

A block scope creates a new variable x = 20 which shadows the outer x. First print outputs 20, then the block ends, outer x (10) is printed.

Take Test

Q.40 Medium Basics & Syntax

Which of the following is a feature of Java 8 that allows functional programming?

A Lambda expressions

B Generics

C Annotations

D Enums

Correct Answer: A. Lambda expressions

EXPLANATION

Lambda expressions were introduced in Java 8, enabling functional programming. Syntax: (parameters) -> expression or statement

Take Test

All Subjects & Topics