com.databasesandlife.util.gwt.dropdownhierarchy.client

Class DropDownHierarchy<N>

java.lang.Object

com.google.gwt.user.client.ui.UIObject

com.google.gwt.user.client.ui.Widget

com.google.gwt.user.client.ui.Composite

com.databasesandlife.util.gwt.dropdownhierarchy.client.DropDownHierarchy<N>

Type Parameters:

N - Node Identifier

All Implemented Interfaces:

com.google.gwt.event.shared.HasHandlers, com.google.gwt.user.client.EventListener

public class DropDownHierarchy<N>
extends com.google.gwt.user.client.ui.Composite

Displays a hierarchical choice as a series of drop-downs.

For example consider the tree of options

    +-- A  (can be selected)
    +-- B
        +-- C (can be selected)
        +-- D (can be selected)

Only leaf nodes can be selected. In the above example only A, C and D can be selected. If D is selected then two drop-downs are displayed:

Changing options in the drop-down:

• Changing the top drop-down to A would select the leaf node A, and the second drop-down would disappear.
• Thereafter, selecting B from the single (top) drop-down would select C (the first leaf node accessible under B) and display two drop-downs: the first displaying B (parent node) and the second displaying C (the selected leaf node).

The interfaces Node, LeafNode and NonLeafNode must be implemented by the application program. They have methods such as getParent and getChildren etc.

The application should register a ChangeListener with the object to be notified when the user makes a selection.

A node has an identity. For example, in the above example the nodes are objects, but the client may request that node with an internal String id, "D", be selected. In this case "D" is the identity of the node. The identity may be any object type; The NODE_ID generic parameter specifies what type identifies nodes.

A DropDownHierarchy is a GWT widget which may be included in any GWT application. Make sure that the source is available to the GWT compiler (the source is included in the databasesandlife-util.jar) and add the following line to the application's GWT XML file:

  <inherits name="com.databasesandlife.util.gwt.dropdownhierarchy.DropdownHierarchy"/>

Author:

This source is copyright Adrian Smith and licensed under the LGPL 3.

See Also:

Project on GitHub

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	DropDownHierarchy.ChangeListener<N>
static interface	DropDownHierarchy.LeafNode<N>
static interface	DropDownHierarchy.Node<N>
static class	DropDownHierarchy.NodeNotFoundException
static interface	DropDownHierarchy.NonLeafNode<N>

Nested classes/interfaces inherited from class com.google.gwt.user.client.ui.UIObject

com.google.gwt.user.client.ui.UIObject.DebugIdImpl, com.google.gwt.user.client.ui.UIObject.DebugIdImplEnabled

Field Summary

Fields inherited from class com.google.gwt.user.client.ui.UIObject

DEBUG_ID_PREFIX

Constructor Summary

Constructors

Constructor and Description
DropDownHierarchy(DropDownHierarchy.NonLeafNode<N> rootNode, N selectedNodeId)

Method Summary

Modifier and Type	Method and Description
static <N> DropDownHierarchy<N>	newIgnoreNotFound(DropDownHierarchy.NonLeafNode<N> rootNode, N selectedNodeId)
void	setChangeListener(DropDownHierarchy.ChangeListener<N> c) When the user makes a selection, this change listener should be called.
void	setSelected(N newSelectedNodeId) Changes which node is selected.

Methods inherited from class com.google.gwt.user.client.ui.Composite

isAttached, onBrowserEvent

Methods inherited from class com.google.gwt.user.client.ui.Widget

fireEvent, getParent, removeFromParent, sinkEvents

Methods inherited from class com.google.gwt.user.client.ui.UIObject

addStyleDependentName, addStyleName, ensureDebugId, ensureDebugId, getAbsoluteLeft, getAbsoluteTop, getElement, getOffsetHeight, getOffsetWidth, getStyleName, getStylePrimaryName, getTitle, isVisible, isVisible, removeStyleDependentName, removeStyleName, setHeight, setPixelSize, setSize, setStyleName, setStylePrimaryName, setTitle, setVisible, setVisible, setWidth, toString, unsinkEvents

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

DropDownHierarchy

public DropDownHierarchy(DropDownHierarchy.NonLeafNode<N> rootNode,
                         N selectedNodeId)
                  throws DropDownHierarchy.NodeNotFoundException

Throws:

DropDownHierarchy.NodeNotFoundException

Method Detail

newIgnoreNotFound

public static <N> DropDownHierarchy<N> newIgnoreNotFound(DropDownHierarchy.NonLeafNode<N> rootNode,
                                                         N selectedNodeId)

setChangeListener

public void setChangeListener(DropDownHierarchy.ChangeListener<N> c)

When the user makes a selection, this change listener should be called. Any previous change listener is deleted.

setSelected

public void setSelected(N newSelectedNodeId)
                 throws DropDownHierarchy.NodeNotFoundException

Changes which node is selected. Updates the user-interface to reflect the newly selected node. The change listener is not called.

Throws:

DropDownHierarchy.NodeNotFoundException