IntMap

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edu.emory.mathcs.util
Interface IntMap

All Known Implementing Classes:: AbstractIntMap, HashIntMap

public interface IntMap

An object that maps int keys to values. A map cannot contain duplicate keys; each key can map to at most one value.

The IntMap interface provides three collection views, which allow a map's contents to be viewed as a collection of values, or set of key-value mappings. The order of a map is defined as the order in which the iterators on the map's collection views return their elements. Some map implementations, like the TreeIntMap class, make specific guarantees as to their order; others, like the HashIntMap class, do not.

All general-purpose map implementation classes should provide two "standard" constructors: a void (no arguments) constructor which creates an empty map, and a constructor with a single argument of type IntMap, which creates a new map with the same key-value mappings as its argument. In effect, the latter constructor allows the user to copy any map, producing an equivalent map of the desired class. There is no way to enforce this recommendation (as interfaces cannot contain constructors) but all of the general-purpose map implementations in the SDK comply.

Version:: 1.0

Nested Class Summary

static interface IntMap.Entry
          A map entry (key-value pair).

Method Summary

void clear()
          Removes all mappings from this map (optional operation).

boolean containsKey(int key)
          Returns true if this map contains a mapping for the specified key.

boolean containsValue(java.lang.Object value)
          Returns true if this map maps one or more keys to the specified value.

java.util.Set entrySet()
          Returns a set view of the mappings contained in this map.

boolean equals(java.lang.Object o)
          Compares the specified object with this map for equality.

java.lang.Object get(int key)
          Returns the value to which this map maps the specified key.

int hashCode()
          Returns the hash code value for this map.

boolean isEmpty()
          Returns true if this map contains no key-value mappings.

java.lang.Object put(int key, java.lang.Object value)
          Associates the specified value with the specified key in this map (optional operation).

void putAll(IntMap t)
          Copies all of the mappings from the specified map to this map (optional operation).

java.lang.Object remove(int key)
          Removes the mapping for this key from this map if present (optional operation).

int size()
          Returns the number of key-value mappings in this map.

java.util.Collection values()
          Returns a collection view of the values contained in this map.

Method Detail

size

public int size()

Returns the number of key-value mappings in this map. If the map contains more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE.

isEmpty

public boolean isEmpty()

Returns true if this map contains no key-value mappings.

containsKey

public boolean containsKey(int key)

Returns true if this map contains a mapping for the specified key.

containsValue

public boolean containsValue(java.lang.Object value)

Returns true if this map maps one or more keys to the specified value. More formally, returns true if and only if this map contains at least one mapping to a value v such that (value==null ? v==null : value.equals(v)). This operation will probably require time linear in the map size for most implementations of the Map interface.

get

public java.lang.Object get(int key)

Returns the value to which this map maps the specified key. Returns null if the map contains no mapping for this key. A return value of null does not necessarily indicate that the map contains no mapping for the key; it's also possible that the map explicitly maps the key to null. The containsKey operation may be used to distinguish these two cases.

put

public java.lang.Object put(int key,
                            java.lang.Object value)

Associates the specified value with the specified key in this map (optional operation). If the map previously contained a mapping for this key, the old value is replaced.

remove

public java.lang.Object remove(int key)

Removes the mapping for this key from this map if present (optional operation).

putAll

public void putAll(IntMap t)

Copies all of the mappings from the specified map to this map (optional operation). These mappings will replace any mappings that this map had for any of the keys currently in the specified map.

clear

public void clear()

Removes all mappings from this map (optional operation).

values

public java.util.Collection values()

Returns a collection view of the values contained in this map. The collection is backed by the map, so changes to the map are reflected in the collection, and vice-versa. If the map is modified while an iteration over the collection is in progress, the results of the iteration are undefined. The collection supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Collection.remove, removeAll, retainAll and clear operations. It does not support the add or addAll operations.

entrySet

public java.util.Set entrySet()

Returns a set view of the mappings contained in this map. Each element in the returned set is a IntMap.Entry. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. If the map is modified while an iteration over the set is in progress, the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Set.remove, removeAll, retainAll and clear operations. It does not support the add or addAll operations.

equals

public boolean equals(java.lang.Object o)

Compares the specified object with this map for equality. Returns true if the given object is also a map and the two Maps represent the same mappings. More formally, two maps t1 and t2 represent the same mappings if t1.entrySet().equals(t2.entrySet()). This ensures that the equals method works properly across different implementations of the Map interface.

hashCode

public int hashCode()

Returns the hash code value for this map. The hash code of a map is defined to be the sum of the hashCodes of each entry in the map's entrySet view. This ensures that t1.equals(t2) implies that t1.hashCode()==t2.hashCode() for any two maps t1 and t2, as required by the general contract of Object.hashCode.