Groovy supports operator overloading which makes working with Numbers, Collections, Maps and various other data structures easier to use.
Various operators in Groovy are mapped onto regular Java method calls on objects.
This allows you the developer to provide your own Java or Groovy objects which can take advantage of operator overloading. The following table describes the operators supported in Groovy and the methods they map to.
Operator 
Method 


a + b 
a.plus(b) 

a  b 
a.minus(b) 

a * b 
a.multiply(b) 

a / b 
a.divide(b) 

a 
b 
a.or(b) 
a & b 
a.and(b) 

a++ or ++a 
a.next() 

a or a 
a.previous() 

a[b] 
a.getAt(b) 

a[b] = c 
a.putAt(b, c) 

a << b 
a.leftShift(b) 
Note that all the following comparison operators handle nulls gracefully avoiding the throwing of java.lang.NullPointerException
Operator 
Method 

a == b 
a.equals(b) 
a != b 
! a.equals(b) 
a === b 
a == b in Java (i.e. a and b refer to same object instance) 
a <=> b 
a.compareTo(b) 
a > b 
a.compareTo(b) > 0 
a >= b 
a.compareTo(b) >= 0 
a < b 
a.compareTo(b) < 0 
a <= b 
a.compareTo(b) <= 0 
Notes about operations
Also in Groovy comparison operators handle nulls gracefully. So that a == b will never throw a NullPointerException whether a or b or both are null.
In addition when comparing numbers of different types then type coercion rules apply to convert numbers to the largest numeric type before the comparison. So the following is valid in Groovy