in scala.collection
trait Map

`abstract trait` Map [A, B]
  `extends` java.lang.Object
  `with` scala.PartialFunction[A, B]
  `with` scala.Iterable[scala.Tuple2[A, B]]
  `with` scala.ScalaObject

  This class defines the interface of collections that unambiguously map keys to values (i.e. a key is mapped to at least one value). Class `Map` may only be used for accessing elements from map implementations. Two different extensions of class `Map` in the package `scala.collections.mutable` and `scala.collections.immutable` provide functionality for adding new key/value mappings to a map. The class in the first package is implemented by maps that are modified destructively, whereas the class in the second package is used by functional map implementations that rely on immutable data structures.

Author:
  Matthias Zenger
Version:
  1.1, 02/05/2004

Direct Known Subclasses:
  Map, Map, MapProxy

Def Summary
| `def` apply (key: A) : B Retrieve the value which is associated with the given key. This method throws an exception if there is no mapping from the given key to a value.
| `def` contains (key: A) : scala.Boolean Is the given key mapped to a value by this map?
| `def` default (key: A) : B The default value for the map, returned when a key is not found The method implemented here yields an error, but it might be overridden in subclasses.
`override` | `def` equals (that: scala.Any) : scala.Boolean Compares two maps structurally; i.e. checks if all mappings contained in this map are also contained in the other map, and vice versa.
`abstract` | `def` get (key: A) : scala.Option[B] Check if this map maps `key` to a value and return the value if it exists.
| `def` isDefinedAt (key: A) : scala.Boolean Does this map contain a mapping from the given key to a value?
| `def` isEmpty : scala.Boolean Is this an empty map?
| `def` keys : scala.Iterator[A] Creates an iterator for all keys.
`abstract` | `def` size : scala.Int Compute the number of key-to-value mappings.
`override` | `def` toString : java.lang.String Creates a string representation for this map.
| `def` values : scala.Iterator[B] Creates an iterator for a contained values.

Def Detail

`def` apply (key: A): B

  Retrieve the value which is associated with the given key. This method throws an exception if there is no mapping from the given key to a value.

Parameters:
  `key -` the key
Returns:
  the value associated with the given key.

`def` contains (key: A): scala.Boolean

  Is the given key mapped to a value by this map?

Parameters:
  `key -` the key
Returns:
  true, iff there is a mapping for key in this map

`def` default (key: A): B

  The default value for the map, returned when a key is not found The method implemented here yields an error, but it might be overridden in subclasses.

Parameters:
  `key -` ...

`override def` equals (that: scala.Any): scala.Boolean

  Compares two maps structurally; i.e. checks if all mappings contained in this map are also contained in the other map, and vice versa.

Returns:
  true, iff both maps contain exactly the same mappings.

`abstract def` get (key: A): scala.Option[B]

  Check if this map maps `key` to a value and return the value if it exists.

Parameters:
  `key -` the key of the mapping of interest
Returns:
  the value of the mapping, if it exists

`def` isDefinedAt (key: A): scala.Boolean

  Does this map contain a mapping from the given key to a value?

Parameters:
  `key -` the key
Returns:
  true, iff there is a mapping for key in this map

`def` isEmpty : scala.Boolean

  Is this an empty map?

Returns:
  true, iff the map is empty.

`def` keys : scala.Iterator[A]

  Creates an iterator for all keys.

Returns:
  an iterator over all keys.

`abstract def` size : scala.Int

  Compute the number of key-to-value mappings.

Returns:
  the number of mappings

`override def` toString : java.lang.String

  Creates a string representation for this map.

Returns:
  a string showing all mappings

`def` values : scala.Iterator[B]

  Creates an iterator for a contained values.

Returns:
  an iterator over all values.