Arithmetic Operators

Beginner ~15 min read

Arithmetic operators are the foundation of mathematical processing in Java. They allow you to perform common mathematical operations like addition, subtraction, multiplication, division, and finding the remainder.

Basic Arithmetic Operators

Java provides five basic arithmetic operators:

Operator	Name	Description	Example
`+`	Addition	Adds two values	`x + y`
`-`	Subtraction	Subtracts one value from another	`x - y`
`*`	Multiplication	Multiplies two values	`x * y`
`/`	Division	Divides one value by another	`x / y`
`%`	Modulo	Returns the division remainder	`x % y`

public class ArithmeticOperators {
    public static void main(String[] args) {
        // Basic arithmetic
        int result = 10 + 5;
        System.out.println("10 + 5 = " + result);

result = 10 - 5;
        System.out.println("10 - 5 = " + result);

result = 10 * 5;
        System.out.println("10 * 5 = " + result);

// Integer Division vs Double Division
        System.out.println("\n--- Division ---");
        int intDiv = 10 / 3;
        System.out.println("10 / 3 (int) = " + intDiv); // Truncated!

double doubleDiv = 10.0 / 3.0;
        System.out.println("10.0 / 3.0 (double) = " + doubleDiv); // Precise

// Modulo
        System.out.println("\n--- Modulo ---");
        int remainder = 10 % 3;
        System.out.println("10 % 3 = " + remainder);

// Increment/Decrement
        System.out.println("\n--- Increment ---");
        int x = 5;
        System.out.println("Original x: " + x);
        int y = x++; // Post-increment: use x, then increment
        System.out.println("After y = x++: y is " + y + ", x is " + x);

x = 5; // Reset x
        int z = ++x; // Pre-increment: increment x, then use
        System.out.println("After z = ++x: z is " + z + ", x is " + x);
    }
}

Output

Click Run to execute your code

Integer vs. Floating-Point Division

It's crucial to understand how division works depending on the operand types.

Integer Division: If both operands are integers (e.g., int), the result is an integer. Any decimal part is truncated (thrown away), not rounded.
Example: 5 / 2 equals 2 (not 2.5).
Floating-Point Division: If at least one operand is a floating-point type (e.g., double or float), the result is a floating-point number.
Example: 5.0 / 2 equals 2.5.

The Modulo Operator (%)

The modulo operator returns the remainder of a division operation. It's incredibly useful for checking if a number is even or odd, or for cycling through values.

int remainder = 10 % 3; // Result is 1 (10 / 3 = 3 with remainder 1)
int isEven = 4 % 2;     // Result is 0 (4 divides perfectly by 2)

Increment and Decrement

Java provides shortcut operators to increase or decrease a variable's value by 1.

Operator	Description	Example (assume x = 5)
`++x` (Prefix)	Increments x, then uses the new value	`int y = ++x;` (x is 6, y is 6)
`x++` (Postfix)	Uses the current value of x, then increments it	`int y = x++;` (y is 5, x is 6)
`--x` (Prefix)	Decrements x, then uses the new value	`int y = --x;` (x is 4, y is 4)
`x--` (Postfix)	Uses the current value of x, then decrements it	`int y = x--;` (y is 5, x is 4)

Summary

Math operations work as expected: +, -, *.
Division / truncates decimals if both numbers are integers.
Modulo % gives the remainder.
++ and -- are shortcuts for adding/subtracting 1.
Be careful with postfix vs. prefix increment when using the result in an expression.

Previous Multi-dimensional Arrays

Next Comparison Operators →

Basic Arithmetic Operators

Integer vs. Floating-Point Division

The Modulo Operator (%)

Increment and Decrement

Summary

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