# OrderedCollection(T)

## `OrderedCollection(T)`

The OrderedCollection type provides the shared functionality of the OrderedSet and Sequence collections for which the elements are ordered. The common supertype of OrderedCollection is Collection.

conformsTo `Collection(T)`

Operations

`at(index : Integer[?]) : T[?] invalidating`

The i-th element of ordered collection.

`first() : T[?] invalidating`

The first element in `self`.

`indexOf(obj : OclAny[?]) : Integer[1]`

The index of object obj in the ordered collection.

`last() : T[?] invalidating`

The last element in `self`.