operatorsandspecialsymbols.txt

Kotlin supports the following operators and special symbols:

+, -, *, /, % - mathematical operators

* is also used to pass an array to a vararg parameter.

=

assignment operator.

is used to specify default values for parameters.

+=, -=, *=, /=, %= - augmented assignment operators.

++, -- - increment and decrement operators.

&&, ||, ! - logical 'and', 'or', 'not' operators (for bitwise operations, use the corresponding infix functions instead).

==, != - equality operators (translated to calls of equals() for non-primitive types).

===, !== - referential equality operators.

<, >, <=, >= - comparison operators (translated to calls of compareTo() for non-primitive types).

[, ] - indexed access operator (translated to calls of get and set).

!! asserts that an expression is non-null.

?. performs a safe call (calls a method or accesses a property if the receiver is non-null).

?: takes the right-hand value if the left-hand value is null (the elvis operator).

:: creates a member reference or a class reference.

.. creates a range.

: separates a name from a type in a declaration.

? marks a type as nullable.

->

separates the parameters and body of a lambda expression.

separates the parameters and return type declaration in a function type.

separates the condition and body of a when expression branch.

@

introduces an annotation.

introduces or references a loop label.

introduces or references a lambda label.

references a 'this' expression from an outer scope.

references an outer superclass.

; separates multiple statements on the same line.

$ references a variable or expression in a string template.

_

substitutes an unused parameter in a lambda expression.

substitutes an unused parameter in a destructuring declaration.