JLCA 3.0 - Java Event Model (AWT and Swing)
Java Event Model mechanism is primarily featured by listeners and adapters used to deal with the different types of events fired by AWT, Swing of the user himself. Most of Swing components use new event types and listeners. Java Event Model is mainly converted through towards .NET Framework event delegation model inherent in System.Windows.Forms and System.ComponentModel APIs and, .NET Framework Classes such as System.EventHandler and System.EventArgs.
JLCA 3.0 main conversion about AWT and Swing events takes into account: Most of the Java API Listeners and Adapters in AWT (some in Swing), DragAndDrop Operations and Custom User Events.
Table 27,Table 28,Table 29 and Table 30 show the most relevant details about Java’s Event Model conversion. In a summarized manner, they enunciate the Java Event Model features preserved in converted applications. On the other hand, they suggest the issues that the user should take care while converting applications using events.
Coverage Details
Class / Interface in Package java.awt.event |
Functionality |
JLCA 3.0 Coverage |
Description |
ActionEvent ActionListener |
ActionEvent indicates when a component-defined action occurred. ActionListener is the listener interface for receiving action events. |
Converted |
Converted to System.Windows.Forms.Button.Click, System.Windows.Forms.TextBox.KeyPress, System.Windows.Forms.ListBox.DoubleClick and System.Windows.Forms.MenuItem.Click. |
ActiveEvent |
This is the interface for events that know how dispatch themselves. |
Not Converted |
These events have no equivalent in .NET Framework. |
AdjustmentEvent AdjustmentListener |
AdjustmentEvent is the event emitted by Adjustable objects. AdjustmentListener is the listener interface for receiving adjustment events. |
Converted |
Converted to System.Windows.Forms.Scrollbar.Scroll. |
ComponentEvent ComponentAdapter ComponentListener |
ComponentEvent indicates that a component moved, changed size, or changed visibility. ComponentAdapter & ComponentListener are adapter and listener for receiving componentevents. |
Converted |
Converted to System.Windows.Forms.Control.Resize, System.Windows.Forms.Control.Move and System.Windows.Forms.Control.VisibleChanged. |
ContainerEvent ContainerAdapter ContainerListener |
ContainerEvent indicates when a component was added or removed. ContainerAdapter & ContainerListener are adapter and listener for receiving containerevents. |
Converted |
Converted to System.Windows.Forms.ContainerControl.ControlAdded and System.Windows.Forms.ContainerControl.ControlRemoved |
FocusEvent FocusAdapter FocusListener |
FocusEvent indicates that a Component has gained or lost the input focus. FocusAdapter & FocusListener are Adapter and listener for receiving keyboard focus events on a component. |
Converted |
Converted to System.Windows.Forms.Control.Enter and System.Windows.Forms.Control.Leave. |
HierarchyBoundsAdapter HierarchyBoundsListener |
These are adapter class and listener interface for receiving ancestor moved and resized events. |
Not Converted |
These events have no equivalent in .NET Framework. |
HierarchyEvent HierarchyListener |
These are event and listener for change to hierarchy of component occurs. |
Not Converted |
These events have no equivalent in .NET Framework. |
InputEvent |
This is the root event class for all component-level input events. |
Not Converted |
These events have no equivalent in .NET Framework. |
InputMethodEvent InputMethodListener |
InputMethodEvent contain information about text that is being composed using an input method. InputMethodListener is the listener interface for receiving input method events. |
Not Converted |
These events have no equivalent in .NET Framework. |
InvocationEvent |
This executes the run() method on a Runnable when dispatched by the AWT event dispatcher thread. |
Not Converted |
These events have no equivalent in .NET Framework. |
ItemEvent ItemListener |
ItemEvent indicates that an item is selected or deselected. ItemListener is the listener interface for receiving item events. |
Converted |
Converted to System.Windows.Forms.CheckBox.Click System.Windows.Forms.MenuItem.Click and System.Windows.Forms.ListBox.SelectedIndexChanged. |
KeyEvent KeyListener |
KeyEvent indicates that a keystroke occurred in a component. KeyListener is the listener interface for receiving keyboard events. |
Converted |
Converted to System.Windows.Forms.Control.KeyPress, System.Windows.Forms.Control.KeyDown and System.Windows.Forms.Control.KeyUp. |
MouseEvent MouseListener MouseMotionAdapter MouseMotionListener |
MouseEvent indicates that a mouse action occurred in a component. MouseListener is the listener interface for receiving mouse events. MouseMotionAdapter & MouseMotionListener are the adapter and listener for receiving mouse motion events. |
Converted |
Converted to System.Windows.Forms.Control.Click, System.Windows.Forms.Control.MouseEnter, System.Windows.Forms.Control.MouseLeave, System.Windows.Forms.Control.MouseMove, System.Windows.Forms.Control.MouseDown and System.Windows.Forms.Control.MouseUp. |
TextEvent TextListener |
TextEvent indicates that an object's text changed. TextListener is the listener interface for receiving text events. |
Converted |
Ported to System.Windows.Forms.TextBox.TextChanged. |
WindowEvent WindowAdapter WindowListener |
WindowEvent indicates that a window has changed its status. WindowAdapter & WindowListener are the adapter and listener for receiving window events. |
Converted |
Converted to System.Windows.Forms.Form.Load, System.Windows.Forms.Form.Activated, System.Windows.Forms.Form.Deactivated, System.Windows.Forms.Form.Closed and System.Windows.Forms.Form.Closing. |
Table 27: Java Event Model Conversion Coverage (1) – Package java.awt.event
Class / Interface in Package java.awt.dnd |
Functionality |
JLCA 3.0 Coverage |
Description |
AutoScroll |
Interface that provides auto scrolling facility. |
Not Converted |
It is not converted to .NET Framework as the auto-scrolling is managed implicitly in .NET Framework. |
DnDConstants |
Contains constant values representing the type of action(s) to be performed by a Drag and Drop operation. |
Converted |
Converted to System.Windows.Forms.DragDropEffects. |
DragGestureEvent DragGestureListener |
DragGestureEvent occurs when a particular DragGestureRecognizer detects that a platform dependent drag initiating gesture has occurred on the Component. DragGestureListener is invoked when an object of that class detects a drag initiating gesture. |
Partially Converted |
Core Functionality achieved through DragSource is converted. Advanced functionality is not converted as .NET Framework does not have its equivalent. |
DragGestureRecognizer MouseDragGestureRecognizer |
This is an abstract base class for the specification of a platform-dependent listener that can be associated with a particular Component in order to identify platform-dependent drag initiating gestures. |
Not Converted |
It is not converted to .NET Framework as similar functionality is not available in .NET Framework. |
DragSource DragSourceContext DragSourceDragEvent DragSourceDropEvent DragSourceEvent DragSourceListener |
DragSource is responsible for the initiation of the Drag and Drop operation. DragSourceContext is responsible for managing the initiator side of the Drag and Drop protocol. DragSourceEvent is the base class for DragSourceDrag Event and DragSourceDrop Event. DragSourceListener is the event interface for originators of Drag and Drop operations to track the state of the user's gesture, and to provide appropriate "drag over" feedback to the user throughout the Drag and Drop operation. |
Partially Converted |
Core functionality exposed by these components is converted to .NET Framework. Since Drag n Drop is managed in a different way in .NET Framework, there is no equivalent for these classes but, the functionality is converted to .NET Framework’s Drag n Drop. |
DropTarget DropTargetContext DropTargetDragEvent DropTargetDropEvent DropTargetEvent DropTargetListener |
These are associatedwith a Component when that Component wishes to accept drops during Drag and Drop operations. |
Partially Converted |
Core functionality exposed by these components is converted to .NET Framework. Operations like dragEnter, dragOver, dragExit and drop are being converted. |
InvalidDnDOperationException |
This is thrown by various methods in the java.awt.dnd package. |
Converted |
It is converted to a more general exception (System.Exception) since there is no direct equivalent in .NET Framework. |
Table 28: Java Event Model Conversion Coverage (2) – Package java.awt.dnd
Class / Interface in Package javax.swing.event |
Functionality |
JLCA 3.0 Coverage |
Description |
AncestorEvent AncestorListener |
AncestorEvent occurs when there is a change to ancestor happens. AncestorListener listens for AncestorEvent. |
Not Converted |
These have no equivalent in .NET Framework. |
CaretEvent CaretListener |
CaretEvent occurs when text caret has changed. CaretListener listens for changes in the caret position of a text component. |
Not Converted |
These have no equivalent in .NET Framework. |
ChangeEvent ChangeListener |
ChangeEvent occurs when state has changed in the event source. ChangeListener listens for ChangeEvents. |
Partially Converted |
Only JSlider and JTabbedPane are converted to System.Windows.Forms.TrackBar.ValueChanged and System.Windows.Forms.TabControl.SelectedIndexChanged. |
HyperlinkEvent HyperlinkListener |
HyperlinkEvent occurs when something has happened with respect to a hypertext link. HyperlinkListener listens for HyperlinkEvent |
Partially Converted |
Only JEditorPane is converted to System.Windows.Forms.RichTextBox.LinkClicked. |
InternalFrameEvent InternalFrameListener |
InternalFrameEvent adds support for JInternalFrame objects as the event source. InternalFrameListener is the listener interface for receiving internal frame events. |
Partially Converted |
JInternalFrame is converted. Messages Deiconified and Iconified are not supported. |
javax.swing.Action |
Action interface provides a useful extension to the ActionListener interface in cases where the same functionality may be accessed by several controls. |
Partially Converted |
Only actionPerformed is converted. |
ListDataEvent ListDataListener |
ListDataEvent occurs when list changes. ListDataListener listens for changes in list. |
Not Converted |
These have no equivalent in .NET Framework. |
ListSelectionEvent ListSelectionListener |
ListSelectionEvent occurs when a change in the current selection occurs. ListSelectionListener listens for lists selection value changes. |
Partially Converted |
Only JList is converted to System.Windows.Forms.ListBox.SelectedValueChanged. |
MenuDragMouseEvent MenuDragMouseListener |
MenuDragMouseEvent occurs when menu element has received a MouseEvent under drag conditions. MenuDragMouseListener listens for MenuDragMouseEvent. |
Not Converted |
These have no equivalent in .NET Framework. |
MenuEvent MenuListener |
MenuEvent occurs when a menu has been posted or selected or canceled. MenuListener listener for menu events. |
Partially Converted |
JMenu (message Selected) is converted to System.Windows.Forms.MenuItem.Select. |
MenuKeyEvent MenuKeyListener |
MenuKeyEvent occurs when menu element has received a KeyEvent forwarded to it in a menu tree. MenuKeyListener listens for MenuKeyListener. |
Not Converted |
These have no equivalent in .NET Framework. |
PopupMenuEvent PopupMenuListener |
PopupMenuEvent occurs with regarding to JPopupMenu. PopupMenuListener listens for PopupMenuEvent. |
Partially Converted |
JPopupMenu is converted to System.Windows.Forms.ContextMenu.Popup (message WillBecomeVisible) |
PropertyChangeEvent PropertyChangeListener |
PropertyChangeEvent occurs whenever a bean changes a "bound" or "constrained" property. PropertyChangeListener listens for PropertyChangeEvent. |
Not Converted |
These have no equivalent in .NET Framework. |
TableColumnModelEvent TableColumnModelListener |
TableColumnModelEvent occurs when a table column has been added or moved or removed. TableColumnModelListener listens to changes in a TableColumnModel. |
Partially Converted |
Only converted for messages Added/Removed to System.Data.DataColumnCollection.CollectionChanged. |
TableModelEvent TableModelListener |
TableModelEvent occurs when a table model has changed. TableModelListener listens to changes in a Table Model. |
Converted |
AbstractTableModel is converted to System.Data.DataTable.RowChanged. |
TreeExpansionEvent TreeExpansionListener |
TreeExpansionEventoccurs when a tree expands or collapses a node. TreeExpansionListener listens for TreeExpansionEvent. |
Converted |
Converted to System.Windows.Forms.TreeView.BeforeExpand, System.Windows.Forms.TreeView.BeforeCollapse, System.Windows.Forms.TreeView.AfterExpand and System.Windows.Forms.TreeView.AfterCollapse. |
TreeModelEvent TreeModelListener |
TreeModelEvent occurs when tree model has changed. TreeModelListener listens to changes in a TreeModel. |
Not Converted |
These have no equivalent in .NET Framework. |
TreeSelectionEvent TreeSelectionListener |
TreeSelectionEvent occurs when the selection in a TreeSelectionModel changes. TreeSelectionListener listens for TreeSelectionEvent. |
Converted |
JTree is converted through System.Windows.Forms.TreeView.AfterSelect. |
UndoableEditEvent UndoableEditListener |
UndoableEditEvent occurs when operation that can be undone has occurred. UndoableEditListener listens for undoable operations. |
Not Converted |
These have no equivalent in .NET Framework. |
Table 29: Java Event Model Conversion Coverage (3) – Package javax.swing.event
Issues
Issue |
Description |
Events Equivalence And Event Handling Behavior |
In some cases, Java’s events behave differently to .NET Framework’s equivalent ones in the sense: the events are fired and handled on corresponding controls. So, the behavior of converted applications could be different since the status of the .NET Framework controls slightly differs. Thus, the stabilization of converted applications –in event handling issues- could require reviewing the .NET framework documentation to learn about the specific events used on the application, their collateral effects and the way they are fired and handled on respective controls. |
EventObject.getSource() |
In Java, the use of method java.util.EventObject.getSource() is to identify the event firing a component. In .NET Framework, the sender of the event is passed as parameter to the event handling method. Invocations to getSource() are converted only within event-handling methods (in Java, listener’s methods). So, conversion for method getSource() could require user-intervention if it is up to 2 level of depth. A workaround could require modifying the arguments of the respective routines to the expected correct parameters sent from the event handling routine. |
Event Queue Managing And Low-Level Event Handling |
Accessing of system event queue is converted because there is no centralized mechanism to read events from a queue and post them. Also, low-level event handling –also known as containment model- is not converted in .NET Framework because the heavy centralization and the lack of modularity inherent in this Java’s model, makes it a very particular way to handle events. |
General Issues |
Java Event Model conversion is mostly based on source code patterns. Java’s event notification –through listeners and adapters- is converted to .NET Framework through events and delegates. In .NET Framework, listener and adapter classes are not essential. However, their methods are converted to delegates through delegate System.EventHandler. In this way, the same source methods are notified when events occur. In .NET Framework, Event “listener registration” is performed attaching event handlers (delegates) to the corresponding events. |
User Raised Events |
Events programmatically-raised by the user (not by the GUI normal interaction) through method dispatchEvent() are not completely converted. Only ActionEvent and ItemEvent (for Button, MenuItem and CheckboxMenuItem) are converted through method PerformClick. Remaining user raised events have no equivalent in .NET Framework. A workaround could require designing another way of event notification. |
Table 30: Java Event Model Conversion Issues