edu.umd.cloud9.util.map
Class HMapIL

java.lang.Object
  edu.umd.cloud9.util.map.HMapIL

All Implemented Interfaces:

MapIL, Serializable, Cloneable

public class HMapIL
extends Object
implements MapIL, Cloneable, Serializable

Hash-based implementation of the MapIL interface. MapIL is a specialized variant the standard Java Map interface, except that the keys are hard coded as ints and values are hard coded as longs for efficiency reasons. This implementation was adapted from HashMap version 1.73, 03/13/07. See this benchmark for an efficiency comparison.

See Also:

Serialized Form

Field Summary

Fields inherited from interface edu.umd.cloud9.util.map.MapIL

DEFAULT_VALUE

Constructor Summary

HMapIL()
Constructs an empty HMapIL with the default initial capacity (1024) and the default load factor (0.75).

HMapIL(int initialCapacity)
Constructs an empty HMapIL with the specified initial capacity and the default load factor (0.75).

HMapIL(int initialCapacity, float loadFactor)
Constructs an empty HMapIL with the specified initial capacity and load factor.

HMapIL(MapIL m)
Constructs a new HMapIL with the same mappings as the specified MapIL.

Method Summary

void	clear() Removes all of the mappings from this map.
Object	clone() Returns a shallow copy of this HMapIL instance: the keys and values themselves are not cloned.
boolean	containsKey(int key) Returns true if this map contains a mapping for the specified key.
boolean	containsValue(long value) Returns true if this map contains one or more mappings with the specified value.
int	dot(MapIL m) Computes the dot product of this map with another map.
Set<MapIL.Entry>	entrySet() Returns a Set view of the mappings contained in this map.
long	get(int key) Returns the value to which the specified key is mapped, or throws NoSuchElementException if this map contains no mapping for the key.
MapIL.Entry[]	getEntriesSortedByValue() Returns entries sorted by descending value.
MapIL.Entry[]	getEntriesSortedByValue(int n) Returns top n entries sorted by descending value.
void	increment(int key) Increments the key.
void	increment(int key, long value)
boolean	isEmpty() Returns true if this map contains no key-value mappings.
Set<Integer>	keySet() Returns a Set view of the keys contained in this map.
void	plus(MapIL m) Adds values of keys from another map to this map.
long	put(int key, long value) Associates the specified value with the specified key in this map.
void	putAll(MapIL m) Copies all of the mappings from the specified map to this map.
long	remove(int key) Removes the mapping for a key from this map if it is present.
int	size() Returns the number of key-value mappings in this map.
String	toString()
Collection<Long>	values() Returns a Collection view of the values contained in this map.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface edu.umd.cloud9.util.map.MapIL

equals, hashCode

Constructor Detail

HMapIL

public HMapIL(int initialCapacity,
              float loadFactor)

Constructs an empty HMapIL with the specified initial capacity and load factor.

Parameters:

initialCapacity - the initial capacity

loadFactor - the load factor

Throws:

IllegalArgumentException - if the initial capacity is negative or the load factor is nonpositive

HMapIL

public HMapIL(int initialCapacity)

Constructs an empty HMapIL with the specified initial capacity and the default load factor (0.75).

Parameters:

initialCapacity - the initial capacity.

Throws:

IllegalArgumentException - if the initial capacity is negative.

HMapIL

public HMapIL()

Constructs an empty HMapIL with the default initial capacity (1024) and the default load factor (0.75).

HMapIL

public HMapIL(MapIL m)

Constructs a new HMapIL with the same mappings as the specified MapIL. The HMapIL is created with default load factor (0.75) and an initial capacity sufficient to hold the mappings in the specified MapIL.

Parameters:

m - the map whose mappings are to be placed in this map

Throws:

NullPointerException - if the specified map is null

Method Detail

size

public int size()

Description copied from interface: MapIL

Returns the number of key-value mappings in this map.

Specified by:

size in interface MapIL

Returns:

the number of key-value mappings in this map

isEmpty

public boolean isEmpty()

Description copied from interface: MapIL

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

Specified by:

isEmpty in interface MapIL

Returns:

true if this map contains no key-value mappings

get

public long get(int key)

Description copied from interface: MapIL

Returns the value to which the specified key is mapped, or throws NoSuchElementException if this map contains no mapping for the key.

Specified by:

get in interface MapIL

Parameters:

key - the key whose associated value is to be returned

Returns:

the value to which the specified key is mapped

containsKey

public boolean containsKey(int key)

Description copied from interface: MapIL

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

Specified by:

containsKey in interface MapIL

Parameters:

key - key whose presence in this map is to be tested

Returns:

true if this map contains a mapping for the specified key

put

public long put(int key,
                long value)

Description copied from interface: MapIL

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

Specified by:

put in interface MapIL

Parameters:

key - key with which the specified value is to be associated

value - value to be associated with the specified key

putAll

public void putAll(MapIL m)

Description copied from interface: MapIL

Copies all of the mappings from the specified map to this map.

Specified by:

putAll in interface MapIL

Parameters:

m - mappings to be stored in this map

remove

public long remove(int key)

Description copied from interface: MapIL

Removes the mapping for a key from this map if it is present. No action is performed if this map does not contain the key.

Specified by:

remove in interface MapIL

Parameters:

key - key whose mapping is to be removed from the map

clear

public void clear()

Description copied from interface: MapIL

Removes all of the mappings from this map. The map will be empty after this call returns.

Specified by:

clear in interface MapIL

containsValue

public boolean containsValue(long value)

Description copied from interface: MapIL

Returns true if this map contains one or more mappings with the specified value.

Specified by:

containsValue in interface MapIL

Parameters:

value - value whose presence in this map is to be tested

Returns:

true this map contains one or more mappings with the specified value

clone

public Object clone()

Returns a shallow copy of this HMapIL instance: the keys and values themselves are not cloned.

Overrides:

clone in class Object

Returns:

a shallow copy of this map

keySet

public Set<Integer> keySet()

Description copied from interface: MapIL

Returns a Set view of the keys contained in this map. Note that this is a inefficient operation since it triggers autoboxing of the int keys, which is exactly what this implementation is trying to avoid. Unlike a standard Java Map, values in the backing map cannot be altered with this collection view.

Specified by:

keySet in interface MapIL

Returns:

a set view of the keys contained in this map

values

public Collection<Long> values()

Description copied from interface: MapIL

Returns a Collection view of the values contained in this map. Note that this is a inefficient operation since it triggers autoboxing of the int values, which is exactly what this implementation is trying to avoid. Unlike a standard Java Map, values in the backing map cannot be altered with this collection view.

Specified by:

values in interface MapIL

Returns:

a collection view of the values contained in this map

entrySet

public Set<MapIL.Entry> entrySet()

Description copied from interface: MapIL

Returns a Set view of the mappings contained in this map. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. See Map.entrySet() for more details.

Specified by:

entrySet in interface MapIL

Returns:

a set view of the mappings contained in this map

toString

public String toString()

Overrides:

toString in class Object

plus

public void plus(MapIL m)

Adds values of keys from another map to this map.

Parameters:

m - the other map

dot

public int dot(MapIL m)

Computes the dot product of this map with another map.

Parameters:

m - the other map

increment

public void increment(int key)

Increments the key. If the key does not exist in the map, its value is set to one.

Parameters:

key - key to increment

increment

public void increment(int key,
                      long value)

getEntriesSortedByValue

public MapIL.Entry[] getEntriesSortedByValue()

Returns entries sorted by descending value. Ties broken by the key.

Returns:

entries sorted by descending value

getEntriesSortedByValue

public MapIL.Entry[] getEntriesSortedByValue(int n)

Returns top n entries sorted by descending value. Ties broken by the key.

Parameters:

n - number of entries to return

Returns:

top n entries sorted by descending value