Lesson 2.5: Operators in Java

Introduction

Operators are one of the most important concepts in programming. They are used to perform different types of operations on variables and values, such as addition, comparison, logical operations, and assignment.

For example, when you calculate the total marks of a student, compare two numbers, or check whether a student has passed an exam, you use operators.

Java provides a rich set of operators that make programming easier and more efficient.

In this lesson, you will learn the different types of operators available in Java and how to use them in real-world programs.

Learning Objectives

After completing this lesson, you will be able to:

• Understand what operators are.

• Use arithmetic operators.

• Use assignment operators.

• Use comparison (relational) operators.

• Use logical operators.

• Use unary operators.

• Use increment and decrement operators.

• Write Java programs using different operators.

What is an Operator?

An Operator is a special symbol that performs an operation on one or more operands (values or variables).

Example

int a = 10;
int b = 5;

int sum = a + b;

Here:

• a and b are operands.

• + is the operator.

• sum stores the result.

Types of Operators in Java

Java provides the following types of operators:

1. Arithmetic Operators

2. Assignment Operators

3. Relational (Comparison) Operators

4. Logical Operators

5. Unary Operators

6. Increment and Decrement Operators

7. Ternary Operator

8. Bitwise Operators (Advanced)

In this lesson, we will focus on the most commonly used operators.

1. Arithmetic Operators

Arithmetic operators perform mathematical calculations.

Example Program

public class ArithmeticDemo { public static void main(String[] args) { int a = 20; int b = 6; System.out.println("Addition = " + (a + b)); System.out.println("Subtraction = " + (a - b)); System.out.println("Multiplication = " + (a * b)); System.out.println("Division = " + (a / b)); System.out.println("Remainder = " + (a % b)); } }

Output

Addition = 26
Subtraction = 14
Multiplication = 120
Division = 3
Remainder = 2

2. Assignment Operators

Assignment operators are used to assign values to variables.

Example

int x = 10; x += 5; System.out.println(x);

Output

15

3. Relational (Comparison) Operators

These operators compare two values and return either true or false.

Example

int a = 10; int b = 20; System.out.println(a < b); System.out.println(a == b);

Output

true
false

4. Logical Operators

Logical operators are used to combine two or more conditions.

Example

int age = 20; System.out.println(age >= 18 && age <= 60);

Output

true

5. Unary Operators

Unary operators work with a single operand.

Example

boolean result = true; System.out.println(!result);

Output

false

6. Increment and Decrement Operators

These operators increase or decrease a variable by one.

Increment (++)

int x = 5; x++; System.out.println(x);

Output

6

Decrement (–)

int y = 10; y--; System.out.println(y);

Output

9

Pre-Increment vs Post-Increment

Pre-Increment

int a = 5; System.out.println(++a);

Output

6

The value increases before printing.

Post-Increment

int a = 5; System.out.println(a++); System.out.println(a);

Output

5
6

The value increases after printing.

7. Ternary Operator

The ternary operator is a short form of the if-else statement.

Syntax

condition ? value1 : value2;

Example

int age = 20; String result = (age >= 18) ? "Eligible" : "Not Eligible"; System.out.println(result);

Output

Eligible

8. Bitwise Operators (Introduction)

Bitwise operators perform operations on binary values.

These operators are mainly used in advanced programming and embedded systems.

Operator Precedence

Operators are evaluated according to their priority.

For example:

int result = 10 + 5 * 2;

Output

20

Multiplication is performed before addition.

Use parentheses to control the order of evaluation.

int result = (10 + 5) * 2;

Output

30

Common Mistakes

Using = Instead of ==

Incorrect

if (a = b)

Correct

if (a == b)

Dividing by Zero

int result = 10 / 0;

This causes an ArithmeticException.

Forgetting Parentheses

Incorrect

System.out.println("Sum = " + a + b);

Correct

System.out.println("Sum = " + (a + b));

Best Practices

• Use meaningful variable names.

• Add spaces around operators for better readability.

• Use parentheses when expressions become complex.

• Avoid unnecessary calculations.

Key Points to Remember

• Operators perform operations on variables and values.

• Arithmetic operators are used for calculations.

• Relational operators return true or false.

• Logical operators combine conditions.

• Assignment operators update variable values.

• The ternary operator is a shorthand for if-else.

Lesson Summary

In this lesson, you learned:

• What operators are.

• Different types of operators in Java.

• Arithmetic, assignment, relational, logical, unary, increment/decrement, ternary, and bitwise operators.

• Operator precedence.

• Common programming mistakes.

Operators are essential because almost every Java program uses them for calculations, comparisons, and decision-making.

Practice Questions

1. What is an operator?

2. What is the difference between = and ==?

3. Name five arithmetic operators.

4. What is the purpose of logical operators?

5. Explain the difference between pre-increment and post-increment.

6. What is the ternary operator?

7. What is operator precedence?

8. Why should parentheses be used in complex expressions?

Programming Exercise

Write Java programs to:

1. Perform addition, subtraction, multiplication, division, and modulus.

2. Demonstrate all assignment operators.

3. Compare two numbers using relational operators.

4. Check voting eligibility using logical operators.

5. Demonstrate pre-increment and post-increment.

6. Use the ternary operator to find the larger of two numbers.

Assignment

Create a program named OperatorDemo.java that:

• Accepts two integer values (hardcoded for now).

• Performs all arithmetic operations.

• Demonstrates assignment operators.

• Compares the numbers using relational operators.

• Uses logical operators to evaluate a condition.

• Displays whether the first number is even or odd using the ternary operator.

Next Lesson: Lesson 2.6 – Taking User Input Using Scanner