Package com.jagrosh.jdautilities.commons.utils

Class FixedSizeCache<K,V>

java.lang.Object

com.jagrosh.jdautilities.commons.utils.FixedSizeCache<K,V>

public class FixedSizeCache<K,V>
extends Object

A simple first-in-first-out key-value storage that uses a HashMap to store keys and values while simultaneously registering the keys to an array to maintain a specified maximum capacity.

As new elements are inserted into the cache, older ones may be removed as a result of the cache being at the maximum capacity set at instantiation.

Since:

1.3

Author:

Michael Ritter

Constructor Summary

Constructors

Constructor	Description
FixedSizeCache(int size)	Constructs a new FixedSizeCache with a set maximum capacity.

Method Summary

Modifier and Type	Method	Description
void	add(K key, V value)	Adds a key and pairs it with a value.
boolean	contains(K key)	Checks if this FixedSizeCache contains a key.
V	get(K key)	Retrieves a value from this FixedSizeCache corresponding to the specified key, or null if there is no corresponding value to be retrieved.

Methods inherited from class java.lang.Object

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

Constructor Details

FixedSizeCache

public FixedSizeCache(int size)

Constructs a new FixedSizeCache with a set maximum capacity.

This entity runs on the basis of "first-in-first-out", meaning that elements inserted into the newly constructed cache will remove the oldest ones if the maximum size is already being occupied.

Parameters:

size - The size of the FixedSizeCache to be created.

Method Details

add

public void add(K key,
 V value)

Adds a key and pairs it with a value.

If this FixedSizeCache is already at maximum occupation, this will remove the oldest element.

NOTE: Any inner workings of HashMap#put(Object, Object) still apply when using this method!
It is recommended anyone using this consult the documentation for HashMap.

Parameters:

key - The key to pair with the value

value - The value to pair with the key

See Also:

• HashMap#put(Object, Object)

contains

public boolean contains(K key)

Checks if this FixedSizeCache contains a key.

NOTE: Any inner workings of HashMap#containsKey(Object) still apply when using this method!
It is recommended anyone using this consult the documentation for HashMap.

Parameters:

key - The key to check for

Returns:

true if the FixedSizeCache contains a key, else false

See Also:

• HashMap#containsKey(Object)

get

public V get(K key)

Retrieves a value from this FixedSizeCache corresponding to the specified key, or null if there is no corresponding value to be retrieved.

NOTE: Any inner workings of HashMap#get(Object) still apply when using this method!
It is recommended anyone using this consult the documentation for HashMap.

Parameters:

key - The key to retrieve a value for

Returns:

A value corresponding to the provided key, or null if there was no value to get.

See Also:

• HashMap#get(Object)