General functions

The function...	checks whether...
isEmpty (value)	A value is empty, null or does not contain any element.
isNotEmpty (value)	A value is not empty.
isEqual (value1, value2)	A value is the same as a second value.
isNotEqual (value1, value2)	A value is not the same as a second value.
isIn (value, Collection)	A value is part of a collection.
areIn (Collection values, Collection collection)	A collection is part of another collection.
isAny (Collection, Closure)	Any value of a collection meets the criteria of a validation closure.
isEvery (Collection, Closure)	All values of a collection meet the criteria of a validation closure.
isFalse (value)	A value is false, empty or null according to the Groovy truth. Examples: `isFalse (something)`: returns true if `something` is false. `isFalse (something)`: returns false is `something` is true. `isFalse (false)`: returns true. `isFalse (null)`: returns true.
isTrue (value)	A value is true, empty or null according to the Groovy truth. Examples: `isTrue (something)`: returns false if `something` is false. `isTrue (something)`: returns true is `something` is true. `isTrue (false)`: returns false. `isTrue (null)`: returns true.
isUnique (Collection, Closure)	All values in a collection are unique. Examples: `isUnique ([1,2,3])`: will evaluate to true. `isUnique ([1,2,3,1])`: will evaluate to false. Examples: The closure `{it % 2}` allows only one even and one odd element in the list. `isUnique ([3, 4], {it % 2})`: will evaluate to true. `isUnique ([1, 3, 4], {it % 2})`: will evaluate to false, because both 1 and 3 are odd.
validate (value)	A value is a valid function, accepting any closure that is capable of returning true or false. Tip Validate (value) is a general validation function used to check another function.

isEmpty (value)

A value is empty, null or does not contain any element.

isNotEmpty (value)

A value is not empty.

isEqual (value1, value2)

A value is the same as a second value.

isNotEqual (value1, value2)

A value is not the same as a second value.

isIn (value, Collection)

A value is part of a collection.

areIn (Collection values, Collection collection)

A collection is part of another collection.

isAny (Collection, Closure)

Any value of a collection meets the criteria of a validation closure.

isEvery (Collection, Closure)

All values of a collection meet the criteria of a validation closure.

isFalse (value)

A value is false, empty or null according to the Groovy truth.

Examples:

isFalse (something): returns true if something is false.
isFalse (something): returns false is something is true.
isFalse (false): returns true.
isFalse (null): returns true.

isTrue (value)

A value is true, empty or null according to the Groovy truth.

Examples:

isTrue (something): returns false if something is false.
isTrue (something): returns true is something is true.
isTrue (false): returns false.
isTrue (null): returns true.

isUnique (Collection, Closure)

All values in a collection are unique.

Examples:

isUnique ([1,2,3]): will evaluate to true.
isUnique ([1,2,3,1]): will evaluate to false.

Examples:

The closure {it % 2} allows only one even and one odd element in the list.

isUnique ([3, 4], {it % 2}): will evaluate to true.
isUnique ([1, 3, 4], {it % 2}): will evaluate to false, because both 1 and 3 are odd.

validate (value)

A value is a valid function, accepting any closure that is capable of returning true or false.

Tip Validate (value) is a general validation function used to check another function.