You use last() in OCL to retrieve the final element of a collection; it is for expressions where the collection order is meaningful.

Syntax

collectionExpression.last()

last() returns a value of type T, where T is the type of element in the collection.

How it works

The operator evaluates its operand as a list and returns the last element of that list. This means you can apply it to a collection expression rather than needing to explicitly create a list first.

For example, if a Fruit object has a collection of fruits, the following expression returns the final fruit in that collection:

self.Fruits.last()

If the collection contains, in order, Apple, Banana, and Orange, the expression returns Orange.

Use it when collection order matters

last() selects by position, not by a property value. Use it when the collection already has the order that your expression requires.

For example, this expression obtains the name of the final fruit:

self.Fruits.last().Name

Before using last(), make sure that the collection's order represents what “last” means in your model. For example, a collection may need to be ordered by a date before its last element can represent the most recent item.

Related operators

Use maxValue when you need the highest value in a collection of simple values rather than the final element by collection position. See Documentation:OCL General Operators to find and work with available OCL operators.

See also

• Documentation:OCL General Operators
• Documentation:OCLOperators maxValue
• Documentation:OCLOperators length
• Documentation:OCL Boolean Operators