jjazzboss commented on code in PR #17:
URL:
https://github.com/apache/netbeans-antora-wiki/pull/17#discussion_r2411517586
##########
modules/netbeansdevelopperfaq/pages/DevFaqActionContextSensitive.adoc:
##########
@@ -140,48 +140,74 @@ public class FooAction extends AbstractAction implements
LookupListener, Context
----
-== Deprecated CookieAction
+Let's register the above action and see how it works.
-In many older (pre-NB 6.8) examples you may find
link:{apidoclink}org-openide-nodes/org/openide/util/actions/CookieAction.html[CookieAction].
It should be (but is not) deprecated. The original info is left here for
reference and/or old code maintenance:
+[source,java]
+----
+@ActionID(category = "foocat", id = "org.fooaction")
+@ActionRegistration(displayName = "not_used", lazy = false) // displayName
useless if lazy is false
+@ActionReferences(
+ {
+ @ActionReference(path = "Menu/Edit", position = 100), // add an
entry in the app-level edit menu
+ @ActionReference(path = "Shortcuts", name = "O-Z"), // action
can be directly run with alt-Z
+ @ActionReference(path = "Actions/Popupmenu", position = 3) //
add a menu entry in a contextual popup menu
+ })
+public class FooAction extends AbstractAction implements LookupListener,
ContextAwareAction {
+...
+----
-link:{apidoclink}org-openide-nodes/org/openide/util/actions/CookieAction.html[CookieAction]
is used to write actions that are sensitive to what is in the selected Node(s)
xref:./DevFaqLookup.adoc[Lookup]. You can specify one or more classes that
must be present in the selected xref:./DevFaqWhatIsANode.adoc[Node]'s Lookup,
and some other semantics about enablement.
+When the Netbeans platform application is started:
-Being an older class, under the hood it is using
xref:./DevFaqLookupCookie.adoc[Node.getCookie()], so your action will only be
sensitive to things actually returned by that method - in other words, only
objects that implement the marker interface `Node.Cookie` can work here.
+* a `FooAction` instance is created automatically using the no-arg constructor
when the edit menu is created
+* the same instance is reused and associated to the alt-Z shortcut
+
+As there can be many actions in a platform app, the constructors must be
lightweight. That's why we start listening to the `Lookup.Result` only when the
menu item is about to be displayed.
-== Not-Yet-Official spi.actions
+To further optimize application startup time, you should register your action
with `lazy=true` whenever possible (see limitations in the
`@ActionRegistration` javadoc). In lazy instanciation mode the `displayName`
value (and other optional parameters) is used to build the action menu item,
and the `FooAction` instance is created only when the menu entry (or keyboard
shortcut) is actually selected by user.
-This module is part of the platform as of 6.8, but has not yet become official
API (and nobody seems to be willing to make it stable API, so judge your own
decisions based on this fact). Nonetheless it is there, it is not changing and
straightforward to use. The example below opens a visual editor window if an
instance of RAFDataObject is selected and has a RandomAccessFile in its lookup:
+The `FooAction` no-arg constructor uses the global selection context
(xref:./DevFaqTrackGlobalSelection.adoc[DevFaqTrackGlobalSelection]), i.e.
action will be enabled only when `Whatever` instances are present in the lookup
of the focused `TopComponent`.
+`FooAction` also implements `ContextAwareAction`. This is used by methods
`Utilities.actionsForPath()` and `Actions.actionsToPopup()` when building a
contextual popup menu, for example:
[source,java]
----
+var actions = Utilities.actionsForPath("Actions/Popupmenu");
+var context = myEditorTopComponent.getLookup();
+var popupmenu = Actions.actionsToPopup(actions, context);
+----
+In our case `actionsToPopup()` will find our FooAction_instance and, because
it's a `ContextAwareAction`, will create a menu item based on the the return
value of FooAction_instance `createContextAwareInstance(context)`. The return
value must be considered as a transient instance because a new `FooAction`
instance is created each time the popup menu is built (i.e. if the transient
instance needs to listen to a shared object, you should probably use a
`WeakListener`).
-public final class CustomOpenAction extends
org.netbeans.spi.actions.Single<RAFDataObject>
- {
- public CustomOpenAction() {
- super(RAFDataObject.class, "Open", null);
- }
- @Override
- protected void actionPerformed(RAFDataObject target) {
- //If an editor is already open, just give it focus
- for (TopComponent tc : TopComponent.getRegistry().getOpened()) {
- if (tc instanceof RAFEditor &&
tc.getLookup().lookup(RAFDataObject.class) == target) {
- tc.requestActive();
- return;
- }
- }
- //Nope, need a new editor
- TopComponent editorWindow = null;
- editorWindow = new RAFEditor(target);
- editorWindow.open();
- editorWindow.requestActive();
- }
- @Override
- protected boolean isEnabled(RAFDataObject target) {
- //Make sure there really is a file on disk
- return target.getLookup().lookup(RandomAccessFile.class) != null;
- }
- }
+Note that even if `FooAction` does not implement `ContextAwareAction`,
different `Utilities.actionsForPath()` calls might return different `FooAction`
instances if there is no strong reference on these instances.
+If you need to enforce `FooAction` as a singleton, it's possible to register a
static factory method instead of the class:
+[source,java]
+----
+public class FooAction extends AbstractAction implements LookupListener {
+
+ private FooAction INSTANCE;
+ @ActionID(category = "foocat", id = "org.fooaction")
+ @ActionRegistration(displayName = "not_used", lazy = false) // displayName
useless if lazy is false
+ @ActionReferences(
+ {
+ @ActionReference(path = "Menu/Edit", position = 100), // add an
entry in the app-level edit menu
+ @ActionReference(path = "Shortcuts", name = "O-Z"), // action
can be directly run with alt-Z
+ @ActionReference(path = "Actions/Popupmenu", position = 3) //
add a menu entry in a contextual popup menu
+ })
+ public static FooAction getInstance() {
+ if (INSTANCE==null)
+ {
+ INSTANCE = new FooAction();
+ }
+ return INSTANCE;
+}
+...
----
-Use `ContextAction` instead of `Single` to create actions that operate on
multi-selections.
+
+== Deprecated CookieAction
+
+In many older (pre-NB 6.8) examples you may find
link:{apidoclink}org-openide-nodes/org/openide/util/actions/CookieAction.html[CookieAction].
It should be (but is not) deprecated. The original info is left here for
reference and/or old code maintenance:
Review Comment:
This is the original text, I have not changed it. It says "it should be (but
it is not)"...
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