com.quadrique.jbuildingblocks.core.dataStructure
Class JbbHashMapWithMultipleValuesPerKey<K,V>

java.lang.Object
  com.quadrique.jbuildingblocks.core.dataStructure.JbbHashMapWithMultipleValuesPerKey<K,V>

Type Parameters:

K - the datatype for the Keys

V - the datatype for the Values

public class JbbHashMapWithMultipleValuesPerKey<K,V>
extends Object

This data structure is similar to a HashMap except that the data associated to any given key is a list of values (an ArrrayList instance).
The actual differences are:

• In the add(key,value) method:
  - If there is no such key in the map, an ArrayList instance is created and the value is added to that newly created list.
  - If the given key is already in the map, the new value is added at the end of the list
• In the getValues(key) method: the list of values associated to the key is returned

This class can be seen as a generalisation of the Histogram class in the sense that a set of related values can be grouped together based on a given key.

For instance:

HashMapWithMultipleValuesPerKey<Integer,String> map = new HashMapWithMultipleValuesPerKey<Integer,String>();
map.add(1,"1_red");
map.add(2,"2_yellow");
map.add(3,"3_red");
map.add(2,"2_green");
map.add(3,"3_yellow");
map.add(2,"2_purple");
map.add(2,"2_blue");

System.out.println("\nThe number of keys is: " + map.getNbOfKeys());

System.out.println("\nThe keys are: ");
for(int key : map.keySet())
{
System.out.println("- \"" + key + "\"");
}

for(int key : map.keySet())
{
System.out.println("\nThe value(s) for the key \"" + key + "\" are:");
for(String value : map.get(key))
{
System.out.println("- \"" + value + "\"");
}
}

The corresponding execution results are:

The number of keys is: 3

The keys are:
- "2"
- "1"
- "3"

The value(s) for the key "2" are:
- "2_yellow"
- "2_green"
- "2_purple"
- "2_blue"

The value(s) for the key "1" are:
- "1_red"

The value(s) for the key "3" are:
- "3_red"
- "3_yellow"

Constructor Summary

JbbHashMapWithMultipleValuesPerKey()

Method Summary

void	add(K key, V value)
ArrayList<V>	get(K key)
int	getNbOfKeys()
Set<K>	keySet()
ArrayList<V>	remove(K key)

Methods inherited from class java.lang.Object

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

Constructor Detail

JbbHashMapWithMultipleValuesPerKey

public JbbHashMapWithMultipleValuesPerKey()

Method Detail

add

public void add(K key,
                V value)

Parameters:

key -

value -

getNbOfKeys

public int getNbOfKeys()

Returns:

the number of keys in the map

keySet

public Set<K> keySet()

Returns:

the set of keys in the map

get

public ArrayList<V> get(K key)

Parameters:

key -

Returns:

list with values

remove

public ArrayList<V> remove(K key)