See Operator Overloading for a list of the common operators that Groovy supports.
In addition, Groovy supports the ! (not) operator as follows:
For more details about how expressions are coerced to a boolean value, see: Groovy Truth.
The Spread Operator is used to invoke an action on all items of an aggregate object. It is equivalent to calling the collect method like so:
The action may either be a method call or property access, and returns a list of the items returned from each child call. As an example:
The Spread operator will work as expected with most of the aggregate-like classes within Groovy. You can also customize your own classes to use it by defining your own
iterator() method as this example shows:
Groovy dynamically creates getter method for all your fields that can be referenced as properties:
You can override these getters with your own implementations if you like:
The @ operator allows you to override this behavior and access the field directly, so to extend the previous sample:
It should be mentioned that, while interesting, this is probably not a good thing to do unless you really need to. Overriding a public interface to access the internal state of an object probably means you are about to break something. Not even recommended for use in tests since it increases coupling unnecessarily.
putAt(index, value) for the subscript operator (e.g. foo or foo['bar'], i.e. index is either an int or String)
isCase()for the membership operator (in)
The "Elvis operator" is a shortening of Java's ternary operator. One instance of where this is handy is for returning a 'sensible default' value if an expression resolves to
null. A simple example might look like this:
The Safe Navigation operator is used to avoid a NullPointerException. Typically when you have a reference to an object you might need to verify that it is not null before accessing methods or properties of the object. To avoid this, the safe navigation operator will simply return
null instead of throwing an exception, like so:
For more details, see: Regular Expressions
Useful in comparisons, returns -1 if left is smaller 0 if == to right or 1 if greater than the right
Find with a regular expresion? See Regular Expressions
Get a match via a regex? See Regular Expressions
Can be used to override generated properties to provide access to a field
Used to invoke an action on all items of an aggregate object
Spread Java Field
Amalgamation of the above two
Get a reference to a method, can be useful for creating closures from methods
Used for groovy casting, coercing one type to another.
Can be used as replacement for collection.contains()
Identity check. Since == is overridden in Groovy with the meaning of equality we need some fallback to check for object identity.
returns nulls instead of throwing NullPointerExceptions
Shorter ternary operator