# WeakCache
Date: 2013-02-18

## org.simpleframework.xml.util
Class WeakCache<T>

    java.lang.Object
      org.simpleframework.xml.util.WeakCache<T>

All Implemented Interfaces:
  Cache<T>

    public class WeakCache<T>

extends java.lang.Object
implements Cache<T>

The `WeakCache` object is an implementation of a cache that holds on to cached items only if the key remains in memory. This is effectively like a concurrent hash map with weak keys, it ensures that multiple threads can concurrently access weak hash maps in a way that lowers contention for the locks used.

Author:
  Niall Gallagher

Constructor Summary
`WeakCache()` Constructor for the `WeakCache` object.
`WeakCache(int size)` Constructor for the `WeakCache` object.

Method Summary
`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.
`boolean` `isEmpty()` This method is used to determine if the cache is empty.
`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.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### WeakCache

    public WeakCache()

  Constructor for the `WeakCache` object. This is used to create a cache that stores values in such a way that when the key is garbage collected the value is removed from the map. This is similar to the concurrent hash map.

### WeakCache

    public WeakCache(int size)

  Constructor for the `WeakCache` object. This is used to create a cache that stores values in such a way that when the key is garbage collected the value is removed from the map. This is similar to the concurrent hash map.

  Parameters:
    `size` - this is the number of segments within the cache

Method Detail

### isEmpty

    public boolean isEmpty()

  Description copied from interface: `Cache`
  This method is used to determine if the cache is empty. This is done by checking if there are any elements in the cache. If anything has been cached this will return false.

  Specified by:
    `isEmpty` in interface `Cache<T>`
  Returns:
    this returns true if the cache is empty

### 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