Class LimitedCache<T>

  • All Implemented Interfaces:
    java.io.Serializable, java.lang.Cloneable, java.util.Map<java.lang.Object,​T>, Cache<T>

    public class LimitedCache<T>
    extends java.util.LinkedHashMap<java.lang.Object,​T>
    implements Cache<T>
    The LimitedCache interface is used to represent a cache that will store key value pairs. This implementation is backed by a LinkedHashMap so that only a specific number of elements can be stored in the cache at one time.
    Author:
    Niall Gallagher
    See Also:
    Serialized Form
    • Nested Class Summary

      • Nested classes/interfaces inherited from class java.util.AbstractMap

        java.util.AbstractMap.SimpleEntry<K extends java.lang.Object,​V extends java.lang.Object>, java.util.AbstractMap.SimpleImmutableEntry<K extends java.lang.Object,​V extends java.lang.Object>
    • Constructor Summary

      Constructors 
      Constructor Description
      LimitedCache()
      Constructor of the LimitedCache object.
      LimitedCache​(int capacity)
      Constructor of the LimitedCache object.
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void cache​(java.lang.Object key, T value)
      This method is used to insert a key value mapping in to the cache.
      boolean contains​(java.lang.Object key)
      This is used to determine whether the specified key exists with in the cache.
      T fetch​(java.lang.Object key)
      This method is used to get the value from the cache that is mapped to the specified key.
      protected boolean removeEldestEntry​(java.util.Map.Entry<java.lang.Object,​T> entry)
      This is used to remove the eldest entry from the cache.
      T take​(java.lang.Object key)
      This is used to exclusively take the value mapped to the specified key from the cache.
      • Methods inherited from class java.util.LinkedHashMap

        clear, containsValue, entrySet, forEach, get, getOrDefault, keySet, replaceAll, values
      • Methods inherited from class java.util.HashMap

        clone, compute, computeIfAbsent, computeIfPresent, containsKey, isEmpty, merge, put, putAll, putIfAbsent, remove, remove, replace, replace, size
      • Methods inherited from class java.util.AbstractMap

        equals, hashCode, toString
      • Methods inherited from class java.lang.Object

        finalize, getClass, notify, notifyAll, wait, wait, wait
      • Methods inherited from interface org.simpleframework.xml.util.Cache

        isEmpty
      • Methods inherited from interface java.util.Map

        compute, computeIfAbsent, computeIfPresent, containsKey, equals, hashCode, isEmpty, merge, put, putAll, putIfAbsent, remove, remove, replace, replace, size
    • Constructor Detail

      • LimitedCache

        public LimitedCache()
        Constructor of the LimitedCache object. This is used to create a cache with a fixed size. The strategy for this cache is least recently used. Any insert or fetch from the cache is considered to be a use.
      • LimitedCache

        public LimitedCache​(int capacity)
        Constructor of the LimitedCache object. This is used to create a cache with a fixed size. The strategy for this cache is least recently used. Any insert or fetch from the cache is considered to be a use.
        Parameters:
        capacity - this is the capacity of the cache object
    • Method Detail

      • cache

        public void cache​(java.lang.Object key,
                          T value)
        This method is used to insert a key value mapping in to the cache. The value can later be retrieved or removed from the cache if desired. If the value associated with the key is null then nothing is stored within the cache.
        Specified by:
        cache in interface Cache<T>
        Parameters:
        key - this is the key to cache the provided value to
        value - this is the value that is to be cached
      • take

        public T take​(java.lang.Object key)
        This is used to exclusively take the value mapped to the specified key from the cache. Invoking this is effectively removing the value from the cache.
        Specified by:
        take in interface Cache<T>
        Parameters:
        key - this is the key to acquire the cache value with
        Returns:
        this returns the value mapped to the specified key
      • fetch

        public T fetch​(java.lang.Object key)
        This method is used to get the value from the cache that is mapped to the specified key. If there is no value mapped to the specified key then this method will return a null.
        Specified by:
        fetch in interface Cache<T>
        Parameters:
        key - this is the key to acquire the cache value with
        Returns:
        this returns the value mapped to the specified key
      • contains

        public boolean contains​(java.lang.Object key)
        This is used to determine whether the specified key exists with in the cache. Typically this can be done using the fetch method, which will acquire the object.
        Specified by:
        contains in interface Cache<T>
        Parameters:
        key - this is the key to check within this segment
        Returns:
        true if the specified key is within the cache
      • removeEldestEntry

        protected boolean removeEldestEntry​(java.util.Map.Entry<java.lang.Object,​T> entry)
        This is used to remove the eldest entry from the cache. The eldest entry is removed from the cache if the size of the map grows larger than the maximum entries permitted.
        Overrides:
        removeEldestEntry in class java.util.LinkedHashMap<java.lang.Object,​T>
        Parameters:
        entry - this is the eldest entry that can be removed
        Returns:
        this returns true if the entry should be removed