com.google.gwt.storage.client

## Class StorageImpl

- java.lang.Object
- - com.google.gwt.storage.client.StorageImpl

- Direct Known Subclasses:
    StorageImplNonNativeEvents

       class StorageImpl
      extends java.lang.Object

  This is the HTML5 Storage implementation according to the standard recommendation.

  Never use this class directly, instead use `Storage`.

  See Also:
    W3C Web Storage - Storage

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `protected static JavaScriptObject` | `jsHandler`
    `static java.lang.String` | `LOCAL_STORAGE`
    `static java.lang.String` | `SESSION_STORAGE`
    `protected static java.util.List<StorageEvent.Handler>` | `storageEventHandlers`

  - ### Constructor Summary

    Constructors
    Modifier | Constructor and Description
    --- | ---
    `protected` | `StorageImpl()` This class can never be instantiated by itself.

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `HandlerRegistration` | `addStorageEventHandler(StorageEvent.Handler handler)` Registers an event handler for StorageEvents.
    `protected void` | `addStorageEventHandler0()`
    `void` | `clear(java.lang.String storage)` Removes all items in the Storage.
    `java.lang.String` | `getItem(java.lang.String storage, java.lang.String key)` Returns the item in the Storage associated with the specified key.
    `int` | `getLength(java.lang.String storage)` Returns the number of items in this Storage.
    `protected java.util.List<StorageEvent.Handler>` | `getStorageEventHandlers()` Returns the `List` of `StorageEvent.Handler`s registered, which is never `null`.
    `protected Storage` | `getStorageFromEvent(StorageEvent event)` Returns the `Storage` object that was affected in the event.
    `protected static void` | `handleStorageEvent(StorageEvent event)` Handles StorageEvents if a `StorageEvent.Handler` is registered.
    `protected static boolean` | `hasStorageEventHandlers()` Returns `true` if at least one StorageEvent handler is registered, `false` otherwise.
    `java.lang.String` | `key(java.lang.String storage, int index)` Returns the key at the specified index.
    `void` | `removeItem(java.lang.String storage, java.lang.String key)` Removes the item in the Storage associated with the specified key.
    `void` | `removeStorageEventHandler(StorageEvent.Handler handler)` De-registers an event handler for StorageEvents.
    `protected void` | `removeStorageEventHandler0()`
    `void` | `setItem(java.lang.String storage, java.lang.String key, java.lang.String data)` Sets the value in the Storage associated with the specified key to the specified data.

    - ### Methods inherited from class java.lang.Object

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

- - ### Field Detail

    - #### LOCAL_STORAGE

          public static final java.lang.String LOCAL_STORAGE

      See Also:
        Constant Field Values

    - #### SESSION_STORAGE

          public static final java.lang.String SESSION_STORAGE

      See Also:
        Constant Field Values

    - #### storageEventHandlers

          protected static java.util.List<StorageEvent.Handler> storageEventHandlers

    - #### jsHandler

          protected static JavaScriptObject jsHandler

  - ### Constructor Detail

    - #### StorageImpl

          protected StorageImpl()

      This class can never be instantiated by itself.

  - ### Method Detail

    - #### handleStorageEvent

          protected static final void handleStorageEvent(StorageEvent event)

      Handles StorageEvents if a `StorageEvent.Handler` is registered.

    - #### hasStorageEventHandlers

          protected static boolean hasStorageEventHandlers()

      Returns `true` if at least one StorageEvent handler is registered, `false` otherwise.

    - #### addStorageEventHandler

          public HandlerRegistration addStorageEventHandler(StorageEvent.Handler handler)

      Registers an event handler for StorageEvents.
      Parameters:
        `handler` -
      Returns:
        `HandlerRegistration` used to remove this handler
      See Also:
        W3C Web Storage - the storage event

    - #### clear

          public void clear(java.lang.String storage)

      Removes all items in the Storage.
      Parameters:
        `storage` - either `LOCAL_STORAGE` or `SESSION_STORAGE`
      See Also:
        W3C Web Storage - Storage.clear()

    - #### getItem

          public java.lang.String getItem(java.lang.String storage,
                                 java.lang.String key)

      Returns the item in the Storage associated with the specified key.
      Parameters:
        `storage` - either `LOCAL_STORAGE` or `SESSION_STORAGE`
        `key` - the key to a value in the Storage
      Returns:
        the value associated with the given key
      See Also:
        W3C Web Storage - Storage.getItem(k)

    - #### getLength

          public int getLength(java.lang.String storage)

      Returns the number of items in this Storage.
      Parameters:
        `storage` - either `LOCAL_STORAGE` or `SESSION_STORAGE`
      Returns:
        number of items in this Storage
      See Also:
        W3C Web Storage - Storage.length()

    - #### key

          public java.lang.String key(java.lang.String storage,
                             int index)

      Returns the key at the specified index.
      Parameters:
        `storage` - either `LOCAL_STORAGE` or `SESSION_STORAGE`
        `index` - the index of the key
      Returns:
        the key at the specified index in this Storage
      See Also:
        W3C Web Storage - Storage.key(n)

    - #### removeItem

          public void removeItem(java.lang.String storage,
                        java.lang.String key)

      Removes the item in the Storage associated with the specified key.
      Parameters:
        `storage` - either `LOCAL_STORAGE` or `SESSION_STORAGE`
        `key` - the key to a value in the Storage
      See Also:
        W3C Web Storage - Storage.removeItem(k)

    - #### removeStorageEventHandler

          public void removeStorageEventHandler(StorageEvent.Handler handler)

      De-registers an event handler for StorageEvents.
      Parameters:
        `handler` -
      See Also:
        W3C Web Storage - the storage event

    - #### setItem

          public void setItem(java.lang.String storage,
                     java.lang.String key,
                     java.lang.String data)

      Sets the value in the Storage associated with the specified key to the specified data.
      Parameters:
        `storage` - either `LOCAL_STORAGE` or `SESSION_STORAGE`
        `key` - the key to a value in the Storage
        `data` - the value associated with the key
      See Also:
        W3C Web Storage - Storage.setItem(k,v)

    - #### addStorageEventHandler0

          protected void addStorageEventHandler0()

    - #### getStorageEventHandlers

          protected java.util.List<StorageEvent.Handler> getStorageEventHandlers()

      Returns the `List` of `StorageEvent.Handler`s registered, which is never `null`.

    - #### getStorageFromEvent

          protected Storage getStorageFromEvent(StorageEvent event)

      Returns the `Storage` object that was affected in the event.
      Returns:
        the `Storage` object that was affected in the event.

    - #### removeStorageEventHandler0

          protected void removeStorageEventHandler0()