# Collection

## `Collection`

Supertype: `Object`

Table 8. Properties

Type | Name | Description
--- | --- | ---
`Boolean` | `isEmpty` | returns true if this Collection is empty
`Integer` | `size` | returns the size of this Collection

Table 9. Operations

Return type | Name | Description
--- | --- | ---
`Boolean` | `contains` ( `Object` ) | returns true if this collection contains the specified object. otherwise false. returns this Collection.
`List` | `toList` () | converts this collection to List
`Set` | `toSet` () | converts this collection to Set
`List` | `flatten` () | returns a flattened List.
`Set` | `intersect` ( `Collection` ) | returns a new Set, containing only the elements contained in this and the specified Collection
`String` | `toString` ( `String` ) | concatenates each contained element (using toString()), separated by the specified String.
`Collection` | `removeAll` ( `Object` ) | removes all elements contained in the specified collection from this Collection if contained (modifies it!). returns this Collection.
`Collection` | `remove` ( `Object` ) | removes the specified element from this Collection if contained (modifies it!). returns this Collection.
`Set` | `without` ( `Collection` ) | returns a new Set, containing all elements from this Collection without the elements from specified Collection
`Collection` | `addAll` ( `Collection` ) | adds all elements to the Collection (modifies it!). returns this Collection.
`Collection` | `add` ( `Object` ) | adds an element to the Collection (modifies it!). returns this Collection.
`Set` | `union` ( `Collection` ) | returns a new Set, containing all elements from this and the specified Collection
`Boolean` | `containsAll` ( `Collection` ) | returns true if this collection contains each element contained in the specified collection. otherwise false. returns this Collection.