Menu Contributions/Radio Button Command
October 2, 2025 · View on GitHub
Eclipse 3.5 or later
You can create a command with a required parameter. The parameter will be passed during every execution.
Command Definition
Define a command with a state and a parameter. The state id should be org.eclipse.ui.commands.radioState and the parameter id should be org.eclipse.ui.commands.radioStateParameter.
<command
defaultHandler="com.example.RadioHandler"
id="z.ex.dropdown.internal.RadioHandler"
name="Radio Example">
<commandParameter
id="org.eclipse.ui.commands.radioStateParameter"
name="Radio Name"
optional="false">
</commandParameter>
<state
class="org.eclipse.ui.handlers.RadioState:Moe"
id="org.eclipse.ui.commands.radioState">
</state>
</command>
Alternatively, the state can be initialized with a default value, which will be checked initially in the Menu. Persistence and default value can be set by parameters for org.eclipse.ui.handlers.RadioState class. The above state section would then be replaced by the following.
<state
id="org.eclipse.ui.commands.radioState">
<class
class="org.eclipse.ui.handlers.RadioState">
<parameter
name="default"
value="Moe">
</parameter>
<parameter
name="persisted"
value="false">
</parameter>
</class>
</state>
Handler
The handler will receive the parameter. It can then update its model (in my example my model is a local variable, but that might not be appropriate in command that can have multiple handlers).
package com.example;
public class RadioHandler extends AbstractHandler{
public Object execute(ExecutionEvent event) throws ExecutionException {
if(HandlerUtil.matchesRadioState(event))
return null; // we are already in the updated state - do nothing
String currentState = event.getParameter(RadioState.PARAMETER_ID);
// do whatever having "currentState" implies
// and finally update the current state
HandlerUtil.updateRadioState(event.getCommand(), currentState);
return null;
}
}
Menu Contribution
Then you add menu contributions with the specific parameters that you want:
<menuContribution
locationURI="menu:help?after=additions">
<separator
name="z.ex.dropdown.menu.separator1"
visible="true">
</separator>
<command
commandId="z.ex.dropdown.radio"
id="z.ex.dropdown.menu.radio1"
label="Moe"
style="radio">
<parameter
name="org.eclipse.ui.commands.radioStateParameter"
value="Moe">
</parameter>
</command>
<command
commandId="z.ex.dropdown.radio"
id="z.ex.dropdown.menu.radio2"
label="Larry"
style="radio">
<parameter
name="org.eclipse.ui.commands.radioStateParameter"
value="Larry">
</parameter>
</command>
<command
commandId="z.ex.dropdown.radio"
id="z.ex.dropdown.menu.radio3"
label="Curly"
style="radio">
<parameter
name="org.eclipse.ui.commands.radioStateParameter"
value="Curly">
</parameter>
</command>
<separator
name="z.ex.dropdown.menu.separator2"
visible="true">
</separator>
</menuContribution>
Eclipse 3.4 or earlier
You can create a command with a required parameter. The parameter will be passed during every execution.
Command Definition
You want to create a command that will be executed with a paramter. The parameter in this example matches which of the radio buttons is selected.
<command
categoryId="org.eclipse.ui.category.help"
defaultHandler="z.ex.dropdown.internal.RadioHandler"
id="z.ex.dropdown.radio"
name="Radio Example">
<commandParameter
id="z.ex.dropdown.radio.info"
name="Radio Name"
optional="false">
</commandParameter>
</command>
Handler
The handler will receive the parameter. It can then update its model (in my example my model is a local variable, but that might not be appropriate in command that can have multiple handlers).
package com.example.handlers.internal;
import java.util.Map;
import org.eclipse.core.commands.AbstractHandler;
import org.eclipse.core.commands.ExecutionEvent;
import org.eclipse.core.commands.ExecutionException;
import org.eclipse.ui.commands.ICommandService;
import org.eclipse.ui.commands.IElementUpdater;
import org.eclipse.ui.handlers.HandlerUtil;
import org.eclipse.ui.menus.UIElement;
public class RadioHandler extends AbstractHandler implements IElementUpdater {
private static final String PARM_INFO = "z.ex.dropdown.radio.info";
private String fCurrentValue;
public Object execute(ExecutionEvent event) throws ExecutionException {
String parm = event.getParameter(PARM_INFO);
if (parm.equals(fCurrentValue)) {
return null; // in theory, we're already in the correct state
}
// do whatever having "parm" active implies
fCurrentValue = parm;
// update our radio button states ... get the service from
// a place that's most appropriate
ICommandService service = (ICommandService) HandlerUtil
.getActiveWorkbenchWindowChecked(event).getService(
ICommandService.class);
service.refreshElements(event.getCommand().getId(), null);
return null;
}
public void updateElement(UIElement element, Map parameters) {
String parm = (String) parameters.get(PARM_INFO);
if (parm != null) {
if (fCurrentValue != null && fCurrentValue.equals(parm)) {
element.setChecked(true);
} else {
element.setChecked(false);
}
}
}
}
Menu Contribution
Then you add menu contributions with the specific parameters that you want:
<menuContribution
locationURI="menu:help?after=additions">
<separator
name="z.ex.dropdown.menu.separator1"
visible="true">
</separator>
<command
commandId="z.ex.dropdown.radio"
id="z.ex.dropdown.menu.radio1"
label="Moe"
style="radio">
<parameter
name="z.ex.dropdown.radio.info"
value="Moe">
</parameter>
</command>
<command
commandId="z.ex.dropdown.radio"
id="z.ex.dropdown.menu.radio2"
label="Larry"
style="radio">
<parameter
name="z.ex.dropdown.radio.info"
value="Larry">
</parameter>
</command>
<command
commandId="z.ex.dropdown.radio"
id="z.ex.dropdown.menu.radio3"
label="Curly"
style="radio">
<parameter
name="z.ex.dropdown.radio.info"
value="Curly">
</parameter>
</command>
<separator
name="z.ex.dropdown.menu.separator2"
visible="true">
</separator>
</menuContribution>
Initializing the Handler
It may happen that your radio menu contributions are not initialized the first time the menu is displayed. This is because at this time, your Handler might not yet have been instantiated (this is due to Eclipse's lazy loading policy). If this is the case, you can enforce the instantiation of your Handler within the Activator of your plug-in. Just add the following code to the start(BundleContext) method:
UIJob job = new UIJob("InitCommandsWorkaround") {
public IStatus runInUIThread(@SuppressWarnings("unused") IProgressMonitor monitor) {
ICommandService commandService = (ICommandService) PlatformUI
.getWorkbench().getActiveWorkbenchWindow().getService(
ICommandService.class);
Command command = commandService.getCommand("z.ex.dropdown.radio");
command.isEnabled();
return new Status(IStatus.OK,
"my.plugin.id",
"Init commands workaround performed successfully");
}
};
job.schedule();