Expressions and Operators

Expressions
An expression is a construct made up of variables, operators, and method invocations that evaluates to a single value.

Expression Operators
Expressions can be joined to one another with operators to create compound expressions.

Safe Navigation Operator
Use the safe navigation operator (?.) to replace explicit, sequential checks for null references. This operator short-circuits expressions that attempt to operate on a null value and returns null instead of throwing a NullPointerException.

Operator Precedence
Operators are interpreted in order, according to rules.

Comments
Both single and multiline comments are supported in Apex code.

Apex Developer Guide

See Also