Package cpsc331.collections

Class OpenHashMap<K,V>

java.lang.Object

cpsc331.collections.OpenHashMap<K,V>

All Implemented Interfaces:

Mapping<K,V>

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

Implements a Mapping using a hash table with open addressing.

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method	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.
void	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

OpenHashMap

public OpenHashMap()

Default constructor uses a hash table with size 23.

OpenHashMap

public OpenHashMap(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.lang.NullPointerException,
             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.lang.NullPointerException - if the input key is null

java.util.NoSuchElementException - if the key is not null, but 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 k is null then a NullPointerException is thrown.
4. Otherwise (that is, if k is not null), 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)
         throws java.lang.NullPointerException

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

Throws:

java.lang.NullPointerException - if k is null

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 k is null then a NullPointerException is thrown.
3. Otherwise (that is, if k is not null), 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 void remove(K k)
            throws java.lang.NullPointerException,
                   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

Throws:

java.lang.NullPointerException - if k is null

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 k is null then a NullPointerException is thrown.
3. Otherwise (that is, if k is not null) if this Mapping includes an ordered pair (k, v) whose first entry is the input key k then this ordered pair is removed; no other changes are made. Otherwise a NoSuchElementException is thrown and this Mapping is not changed at all.