cpsc331.collections

Class ChainHashMap<K,V>

java.lang.Object

cpsc331.collections.ChainHashMap<K,V>

All Implemented Interfaces:

Mapping<K,V>

public class ChainHashMap<K,V>
extends java.lang.Object
implements Mapping<K,V>

Implements a Mapping using a hash table with chaining..

Constructor Summary

Constructors

Constructor and Description
ChainHashMap() Default constructor uses a hash table with size 23.
ChainHashMap(int s) Constructor receives table size as input.

Method Summary

Modifier and Type	Method and Description
V	get(K k) Returns the value associated with a given key, throwing a NoSuchElementException if no value is currently associated with the given key.
V	remove(K k) Removes the ordered pair with a given input key k, returning a NoSuchElementException and leaving the Mapping unchanged if no such ordered pair exists.
void	set(K k, V v) Sets the value associated with an input key to be an input value — replacing the value formerly associated with this key if one already exists.

Methods inherited from class java.lang.Object

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

Methods inherited from interface cpsc331.collections.Mapping

defined

Constructor Detail

ChainHashMap

public ChainHashMap()

Default constructor uses a hash table with size 23.

ChainHashMap

public ChainHashMap(int s)

Constructor receives table size as input.

Parameters:

s - size of hash table to be used

Throws:

java.lang.IllegalArgumentException - if s is not positive

Method Detail

get

public V get(K k)
      throws java.util.NoSuchElementException

Description copied from interface: Mapping

Returns the value associated with a given key, throwing a NoSuchElementException if no value is currently associated with the given key.

Specified by:

get in interface Mapping<K,V>

Parameters:

k - the key whose value is to be returned

Returns:

the value of this key

Throws:

java.util.NoSuchElementException - if no value is defined for this key

Precondition:

1. The Mapping Invariant is satisfied.
2. A value k with type K has been provided as input.

Postcondition:

1. The Mapping Invariant is satisfied.
2. This Mapping has not been changed.
3. If this Mapping includes some ordered pair whose first entry is the input key k, then the value v that is the second entry of this ordered pair (that is, the value associated with k) is returned as output. A NoSuchElementException is thrown otherwise.

set

public void set(K k,
                V v)

Description copied from interface: Mapping

Sets the value associated with an input key to be an input value — replacing the value formerly associated with this key if one already exists.

Specified by:

set in interface Mapping<K,V>

Parameters:

k - the key for which a value is to be defined

v - the value that is to be defined to this key

Precondition:

1. The Mapping Invariant is satisfied.
2. A value k with type K and v with type V are provided as input.

Postcondition:

1. The Mapping Invariant is satisfied.
2. If this Mapping included an ordered pair whose first entry is the input value k, then this is replaced by the ordered pair (k, v). Otherwise a new ordered pair (k, v) is added. No other changes to this Mapping are made.

remove

public V remove(K k)
         throws java.util.NoSuchElementException

Description copied from interface: Mapping

Removes the ordered pair with a given input key k, returning a NoSuchElementException and leaving the Mapping unchanged if no such ordered pair exists.

Specified by:

remove in interface Mapping<K,V>

Parameters:

k - the key for which a value is to be undefined

Returns:

the former value of this key

Throws:

java.util.NoSuchElementException - if no value was defined for this key

Precondition:

1. The Dictionary Invariant is satisfied.
2. A value k with type K is provided as input.

Postcondition:

1. The Mapping Invariant is satisfied.
2. If this Mapping includes an ordered pair (k, v) whose first entry is the input key k then this ordered pair is removed and the second entry v (that is, the value associated with this key) is returned as output; no other changes are made. Otherwise a NoSuchElementException is thrown and this Mapping is not changed at all.