25. Numeric Operators

The following chapters will describe each of the numerical operators in further detail. In this tutorial I just lay the list of operators out for you to quickly see and then describe operator precedence - the order in which the operators are evaluated.

Operator Precedence

Operator precedence describes the order in which operators are evaluated. For example, most people know that the multiplication operator is evaluated before the addition, resulting in the following code displaying 20 (and not 60):

println 10 + 2 * 5

Parentheses can be used to denote the need for an operator to be evaluated first, allowing the following code to give us 60:

def result = (10 + 2) * 5
println result

Operators with the same (equal) precedence (e.g. + and -) are evaluated depending on their associativity. There are three types of associativity:

• Left-associative: where the operators are grouped left to right
• Associative: where operators are grouped arbitrarily
  • Not seen in Groovy
• Right-associative: where the operators are grouped right to left

For example, the additive operators (+ and -) are left associative, meaning that they are evaluated left to right. The expression 6 + 2 - 4 is evaluated as the result of 6 + 2 minus 4.

The simple assignment operator (=) is right associative, resulting in the following code displaying a result of 2:

def a = 10
def b = 5
def c = 2

a = b = c

println a

Order of Precedence

The order of precedence (highest to lowest) for the arithmetic operators is as follows: