Commands
See the
org.eclipse.ui.commands
section for defining command definitions.
Associating an action with a command
Actions can be associated with a command in code or in the plugin.xml
for action sets.
Your choice depends on where the action is defined.
Actions that are instantiated in code can also be associated with an action
definition using
IAction
protocol. This is typically done when the action is created. The SaveAction
uses this technique when it initializes itself.
public SaveAction(IWorkbenchWindow window) {
...
setText...
setToolTipText...
setImageDescriptor...
setActionDefinitionId("org.eclipse.ui.file.save");
}
(Note: The method name setActionDefinitionID could more
appropriately be named setCommandID. The method name reflects the
original implementation of key bindings and uses outdated terminology.)
By invoking setActionDefinitionID, the implementation action (SaveAction) is associated with
the command id that was used in the command definition markup. It is good practice to define constants for your action definitions so that
they are easily referenced in code.
If you define an
action in an action set, then you typically do not need to
instantiate an action yourself. The workbench will do it for you when the user
invokes your action from a menu or the keyboard. In this case, you can
associate your action with a command ID in your XML markup. The
following shows a hypothetical markup for an action set:
<extension point = "org.eclipse.ui.actionSets">
<actionSet id="com.example.actions.actionSet"
label="Example Actions"
visible="true">
<action id="com.example.actions.action1"
menubarPath="additions"
label="Example Save Action"
class="org.example.actions.ExampleActionDelegate"
definitionId="org.eclipse.ui.file.save">
</action>
...
</actionSet>
</extension>
The definitionId attribute is used to declare a command ID for the action.
Using either technique, associating your action with a command ID causes any key bindings that get defined for the
command org.eclipse.ui.file.save
to invoke your action when appropriate.
Now let's look at how these key bindings get defined.