Arithmetic & Assignment Operators

Syntax

+  -  *  /  %   +=  -=  ++  --

Examples

int a = 10, b = 3;

System.out.println(a + b);  // 13
System.out.println(a - b);  // 7
System.out.println(a * b);  // 30
System.out.println(a / b);  // 3  (integer division truncates)
System.out.println(a % b);  // 1  (remainder)

double result = 10.0 / 3;    // true division with a double
System.out.println(result); // 3.3333333333333335

int score = 10;
score += 5;   // score = score + 5  -> 15
score -= 3;   // 12
score *= 2;   // 24
score /= 4;   // 6

System.out.println(score);

int x = 5;
System.out.println(x++);  // prints 5, THEN increments (x is now 6)
System.out.println(x);    // 6

int y = 5;
System.out.println(++y);  // increments FIRST, then prints (y is now 6)
System.out.println(y);    // 6

Best practices

• Watch out for integer division truncating results - divide by a double literal (10.0 / 3) when you need a precise decimal result
• Be careful mixing prefix and postfix increment operators within the same complex expression - it can make code hard to reason about
• Use compound assignment operators (+=, -=, etc.) for conciseness when updating a variable based on itself
• Remember % gives the remainder, not a true modulus - it can return negative results when the left-hand operand is negative

At a glance

Purpose

General-purpose application development

File extension

.java

Runs in

Java Virtual Machine

Usually used with

JDK and Java libraries

Specifications & further reading

• Java Language Specification

Related Java documentation