edu.ucla.sspace.util

Class ObjectCounter<T>

java.lang.Object

edu.ucla.sspace.util.ObjectCounter<T>

All Implemented Interfaces:

Counter<T>, Serializable, Iterable<Map.Entry<T,Integer>>

public class ObjectCounter<T>
extends Object
implements Counter<T>, Serializable

A utility for counting unique instance of an object.

This class supports iterating over the set of instances being counted as well as the instances and counts together. All collections views that are returned are unmodifiable and will throw an exception if a mutating method is called.

This class is not thread-safe

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
ObjectCounter() Creates an empty Counter.
ObjectCounter(Collection<? extends T> items) Creates a Counter whose initial state has counted all of the specified items.

Method Summary

Methods

Modifier and Type	Method and Description
void	add(Counter<? extends T> counter) Adds the counts from the provided Counter to the current counts, adding new elements as needed.
int	count(T obj) Counts the object, increasing its total count by 1.
int	count(T obj, int count) Counts the object, increasing its total count by the specified positive amount.
void	countAll(Collection<? extends T> c) Counts all the elements in the collection.
boolean	equals(Object o)
int	getCount(T obj) Returns the number of times the specified object has been seen by this counter.
double	getFrequency(T obj) Returns the frequency of this object relative to the counts of all other objects.
int	hashCode()
Set<T>	items() Returns a view of the items currently being counted.
Iterator<Map.Entry<T,Integer>>	iterator() Returns an interator over the elements that have been counted thusfar and their respective counts.
T	max() Returns the element that currently has the largest count.
T	min() Returns the element that currently has the smallest count.
void	reset() Resets the counts for all objects.
int	size() Returns the number of instances that are currently being counted.
int	sum() Returns the total number of instances that have been counted.
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

ObjectCounter

public ObjectCounter()

Creates an empty Counter.

ObjectCounter

public ObjectCounter(Collection<? extends T> items)

Creates a Counter whose initial state has counted all of the specified items.

Method Detail

add

public void add(Counter<? extends T> counter)

Adds the counts from the provided Counter to the current counts, adding new elements as needed.

Specified by:

add in interface Counter<T>

count

public int count(T obj)

Counts the object, increasing its total count by 1.

Specified by:

count in interface Counter<T>

count

public int count(T obj,
        int count)

Counts the object, increasing its total count by the specified positive amount.

Specified by:

count in interface Counter<T>

Parameters:

count - a positive value for the number of times the object occurred

Returns:

the current count for the counted object

Throws:

IllegalArgumentException - if count is not a positive value.

countAll

public void countAll(Collection<? extends T> c)

Counts all the elements in the collection.

Specified by:

countAll in interface Counter<T>

Parameters:

c - a collection of elements to count

equals

public boolean equals(Object o)

Specified by:

equals in interface Counter<T>

Overrides:

equals in class Object

getCount

public int getCount(T obj)

Returns the number of times the specified object has been seen by this counter.

Specified by:

getCount in interface Counter<T>

getFrequency

public double getFrequency(T obj)

Returns the frequency of this object relative to the counts of all other objects. This value may also be interpreted as the probability of the instance of obj being seen in the items that have been counted.

Specified by:

getFrequency in interface Counter<T>

hashCode

public int hashCode()

Specified by:

hashCode in interface Counter<T>

Overrides:

hashCode in class Object

items

public Set<T> items()

Returns a view of the items currently being counted. The returned view is read-only; any attempts to modify this view will throw an UnsupportedOperationException.

Specified by:

items in interface Counter<T>

iterator

public Iterator<Map.Entry<T,Integer>> iterator()

Returns an interator over the elements that have been counted thusfar and their respective counts.

Specified by:

iterator in interface Counter<T>

Specified by:

iterator in interface Iterable<Map.Entry<T,Integer>>

max

public T max()

Returns the element that currently has the largest count. If no objects have been counted, null is returned. Ties in counts are arbitrarily broken.

Specified by:

max in interface Counter<T>

min

public T min()

Returns the element that currently has the smallest count. If no objects have been counted, null is returned. Ties in counts are arbitrarily broken.

Specified by:

min in interface Counter<T>

reset

public void reset()

Resets the counts for all objects. The size of items() will be 0 after this call.

Specified by:

reset in interface Counter<T>

size

public int size()

Returns the number of instances that are currently being counted.

Specified by:

size in interface Counter<T>

sum

public int sum()

Returns the total number of instances that have been counted.

Specified by:

sum in interface Counter<T>

toString

public String toString()

Overrides:

toString in class Object