Operators in Java

Operators combine values, compare values, or update variables. Understanding the result type and operator precedence helps prevent confusing expressions.

Arithmetic operators#

int a = 10;
int 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
System.out.println(a % b); // 1

When both operands are integers, / performs integer division, so 10 / 3 is 3, not 3.333.... Use a floating-point operand if you need a decimal result.

Comparison operators#

==, !=, >, <, >=, and <= compare values and produce a boolean result. For object references such as strings, == compares whether the references identify the same object; use .equals() when checking string content.

int age = 20;
System.out.println(age >= 18); // true

Logical operators#

• && means AND: both conditions must be true.
• || means OR: at least one condition must be true.
• ! reverses a boolean value.

The && and || operators short-circuit, which means Java may skip evaluating the right-hand side when the result is already known.

Assignment and increment#

int points = 5;
points += 2; // points is now 7
points++;    // points is now 8

Precedence and readability#

Multiplication usually happens before addition, but parentheses make intent clearer:

int result = (2 + 3) * 4; // 20

Prefer small, readable expressions over relying on readers to remember a complicated precedence chain.

Practice#

Create two integer variables and print their sum, difference, product, quotient, and remainder. Try the quotient again after casting one operand to double.