Variables are like containers which holds the data values. A variable specifies the name of the memory location.

How to declare variables

There are three ways to declare variables in Groovy.

  1. Native syntax similar to Java
data-type variable-name = value;
  1. Using def keyword
def variable-name = value;
  1. Variables in groovy do not require a type definition.
variable-name = value; // no type definition is required

In the above syntax, assigning value is optional as you can just declare the variable and then assign value at later point in the program. Also, the value of a variable can be changed at any time.

Naming convention of variables

  • Variable's name should consists of only letters (both uppercase and lowercase letters), digits and underscore(_).
  • Variable's name cannot contain white spaces like first name which is a invalid variable name.
  • First letter of a variable should be either a letter or an underscore(_).
  • Variable names are case sensitive and hence Name and name both are different.
  • It is always advisable to give some meaningful names to variables.


int x = 10; // declaring int variable and assigning value 10 to it
char grade = 'A'; // declaring char variable and assigning value A to it

The above can also be written like below

int x; // declaring int variable 
char grade; // declaring char variable 

x = 10; // assigning value 10 to x variable
grade = 'A'; //and assigning value A to grade variable

Sample program:

int int_var = 99999 // using native method
println int_var;

int_var = 1000;
println int_var;

def x = "hello" // using def keyword
println x

Check result here