Package org.eclipse.ui

Interface IMemento

  • All Known Implementing Classes:
    XMLMemento
    public interface IMemento
    Interface to a memento used for saving the important state of an object in a form that can be persisted in the file system.

    Mementos were designed with the following requirements in mind:

    1. Certain objects need to be saved and restored across platform sessions.
    2. When an object is restored, an appropriate class for an object might not be available. It must be possible to skip an object in this case.
    3. When an object is restored, the appropriate class for the object may be different from the one when the object was originally saved. If so, the new class should still be able to read the old form of the data.

    Mementos meet these requirements by providing support for storing a mapping of arbitrary string keys to primitive values, and by allowing mementos to have other mementos as children (arranged into a tree). A robust external storage format based on XML is used.

    The key for an attribute may be any alpha numeric value that doesn't start with a number. eg: [A-Za-z][A-Za-z0-9]* Using '.' is unsupported. However, the value of TAG_ID is reserved for internal use.

    The default implementation can throw a DOMException for createChild and put operations. See XMLMemento.

    This interface is not intended to be implemented or extended by clients.

    See Also:
    IPersistableElement, IElementFactory, XMLMemento
    Restriction:
    This interface is not intended to be implemented by clients.

    • Method Detail

      • createChild

        IMemento createChild​(String type)
        Creates a new child of this memento with the given type.

        The getChild and getChildren methods are used to retrieve children of a given type.

        Parameters:
        type - the type
        Returns:
        a new child memento
        See Also:
        getChild(java.lang.String), getChildren()

      • createChild

        IMemento createChild​(String type,
                     String id)
        Creates a new child of this memento with the given type and id. The id is stored in the child memento (using a special reserved key, TAG_ID) and can be retrieved using getId.

        The getChild and getChildren methods are used to retrieve children of a given type.

        Parameters:
        type - the type
        id - the child id
        Returns:
        a new child memento with the given type and id
        See Also:
        getID()

      • getChild

        IMemento getChild​(String type)
        Returns the first child with the given type id.
        Parameters:
        type - the type id
        Returns:
        the first child with the given type. May return null .

      • getChildren

        IMemento[] getChildren()
        Returns all children of this node.
        Returns:
        an array of children of this node. This will not be null. If there are no children, an array of length zero will be returned.
        Since:
        3.8

      • getChildren

        IMemento[] getChildren​(String type)
        Returns all children with the given type id.
        Parameters:
        type - the type id
        Returns:
        an array of children with the given type. This will not be null. If there are no keys, an array of length zero will be returned.

      • getFloat

        Float getFloat​(String key)
        Returns the floating point value of the given key.
        Parameters:
        key - the key
        Returns:
        the value, or null if the key was not found or was found but was not a floating point number

      • getInteger

        Integer getInteger​(String key)
        Returns the integer value of the given key.
        Parameters:
        key - the key
        Returns:
        the value, or null if the key was not found or was found but was not an integer

      • getString

        String getString​(String key)
        Returns the string value of the given key.
        Parameters:
        key - the key
        Returns:
        the value, or null if the key was not found

      • getBoolean

        Boolean getBoolean​(String key)
        Returns the boolean value of the given key.
        Parameters:
        key - the key
        Returns:
        the value, or null if the key was not found
        Since:
        3.4

      • getTextData

        String getTextData()
        Returns the data of the Text node of the memento. Each memento is allowed only one Text node.
        Returns:
        the data of the Text node of the memento, or null if the memento has no Text node.
        Since:
        2.0

      • getAttributeKeys

        String[] getAttributeKeys()
        Returns an array of all the attribute keys of the memento. This will not be null. If there are no keys, an array of length zero will be returned.
        Returns:
        an array with all the attribute keys of the memento
        Since:
        3.4

      • putFloat

        void putFloat​(String key,
              float value)
        Sets the value of the given key to the given floating point number.
        Parameters:
        key - the key
        value - the value

      • putInteger

        void putInteger​(String key,
                int value)
        Sets the value of the given key to the given integer.
        Parameters:
        key - the key
        value - the value

      • putMemento

        void putMemento​(IMemento memento)
        Copy the attributes and children from memento to the receiver.
        Parameters:
        memento - the IMemento to be copied.

      • putString

        void putString​(String key,
               String value)
        Sets the value of the given key to the given string.
        Parameters:
        key - the key
        value - the value

      • putBoolean

        void putBoolean​(String key,
                boolean value)
        Sets the value of the given key to the given boolean value.
        Parameters:
        key - the key
        value - the value
        Since:
        3.4

      • putTextData

        void putTextData​(String data)
        Sets the memento's Text node to contain the given data. Creates the Text node if none exists. If a Text node does exist, it's current contents are replaced. Each memento is allowed only one text node.
        Parameters:
        data - the data to be placed on the Text node
        Since:
        2.0