org.millstone.base.data
Interface Container.Hierarchical

All Superinterfaces:

Container

All Known Implementing Classes:

ContainerHierarchicalWrapper, FilesystemContainer, HierarchicalContainer, Tree

Enclosing interface:

Container

public static interface Container.Hierarchical

extends Container

Interface for Container classes whose Items can be arranged hierarchically. This means that the Items in the container belong in a tree-like structure, with the following quirks:

• The Item structure may have more than one root elements
• The Items in the hierarchy can be declared explicitly to be able or unable to have children.

Nested Class Summary

Nested classes inherited from class org.millstone.base.data.Container

Container.Editor, Container.Hierarchical, Container.Indexed, Container.ItemSetChangeEvent, Container.ItemSetChangeListener, Container.ItemSetChangeNotifier, Container.Ordered, Container.PropertySetChangeEvent, Container.PropertySetChangeListener, Container.PropertySetChangeNotifier, Container.Viewer

Field Summary

Fields inherited from interface org.millstone.base.data.Container

NULL_ITEM_ID

Method Summary

boolean	areChildrenAllowed(java.lang.Object itemId) Tests if the Item with given ID can have any children.
java.util.Collection	getChildren(java.lang.Object itemId) Gets the IDs of all Items that are children of the specified Item.
java.lang.Object	getParent(java.lang.Object itemId) Gets the ID of the parent Item of the specified Item.
boolean	hasChildren(java.lang.Object itemId) Tests if the Item specified with itemId has any child Items, that is, is it a leaf Item.
boolean	isRoot(java.lang.Object itemId) Tests if the Item specified with itemId is a root Item.
java.util.Collection	rootItemIds() Gets the IDs of all Items in the container that don't have a parent.
boolean	setChildrenAllowed(java.lang.Object itemId, boolean areChildrenAllowed) Sets the given Item's capability to have children.
boolean	setParent(java.lang.Object itemId, java.lang.Object newParentId) Sets the parent of an Item.

Methods inherited from interface org.millstone.base.data.Container

addContainerProperty, addItem, addItem, containsId, getContainerProperty, getContainerPropertyIds, getItem, getItemIds, getType, removeAllItems, removeContainerProperty, removeItem, size

Method Detail

getChildren

public java.util.Collection getChildren(java.lang.Object itemId)

Gets the IDs of all Items that are children of the specified Item. The returned collection is unmodifiable.

Parameters:

itemId - ID of the Item whose children the caller is interested in

Returns:

An unmodifiable collection containing the IDs of all other Items that are children in the container hierarchy

getParent

public java.lang.Object getParent(java.lang.Object itemId)

Gets the ID of the parent Item of the specified Item.

Parameters:

itemId - ID of the Item whose parent the caller wishes to find out.

Returns:

the ID of the parent Item. Will be null if the specified Item is a root element.

rootItemIds

public java.util.Collection rootItemIds()

Gets the IDs of all Items in the container that don't have a parent. Such items are called root Items. The returned collection is unmodifiable.

Returns:

An unmodifiable collection containing IDs of all root elements of the container

setParent

public boolean setParent(java.lang.Object itemId,
                         java.lang.Object newParentId)
                  throws java.lang.UnsupportedOperationException

Sets the parent of an Item. The new parent item must exist and be able to have children. (canHaveChildren(newParentId) == true). It is also possible to detach a node from the hierarchy (and thus make it root) by setting the parent null.

This operation is optional.

Parameters:

itemId - ID of the item to be set as the child of the Item identified with newParentId

newParentId - ID of the Item that's to be the new parent of the Item identified with itemId

Returns:

true if the operation succeeded, false if not

java.lang.UnsupportedOperationException

areChildrenAllowed

public boolean areChildrenAllowed(java.lang.Object itemId)

Tests if the Item with given ID can have any children. If the Container also implements the Managed interface, the items created with newItem can have children by default.

Parameters:

itemId - ID of the Item in the container whose child capability is to be tested

Returns:

true if the specified Item exists in the Container and it can have children, false if it's not found from the container or it can't have children.

setChildrenAllowed

public boolean setChildrenAllowed(java.lang.Object itemId,
                                  boolean areChildrenAllowed)
                           throws java.lang.UnsupportedOperationException

Sets the given Item's capability to have children. If the Item identified with itemId already has children and areChildrenAllowed is false this method fails and false is returned; the children must be first explicitly removed with setParent(Object itemId, Object newParentId) or Container.removeItem(Object itemId).

This operation is optional. If it is not implemented, the method always returns false.

Parameters:

itemId - ID of the Item in the container whose child capability is to be set

areChildrenAllowed - boolean value specifying if the Item can have children or not

Returns:

true if the operation succeeded, false if not

java.lang.UnsupportedOperationException

isRoot

public boolean isRoot(java.lang.Object itemId)

Tests if the Item specified with itemId is a root Item. The hierarchical container can have more than one root and must have at least one unless it is empty. The getParent(Object itemId) method always returns null for root Items.

Parameters:

itemId - ID of the Item whose root status is to be tested

Returns:

true if the specified Item is a root, false if not

hasChildren

public boolean hasChildren(java.lang.Object itemId)

Tests if the Item specified with itemId has any child Items, that is, is it a leaf Item. The getChildren(Object itemId) method always returns null for leaf Items.

Note that being a leaf does not imply whether or not an Item is allowed to have children.

.

Parameters:

itemId - ID of the Item whose leaf status is to be tested

Returns:

true if the specified Item is a leaf, false if not