Package org.eclipse.core.commands
Interface IHandler
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- All Known Subinterfaces:
IHandler2
- All Known Implementing Classes:
AbstractHandler,AbstractHandler,AbstractHandlerWithState,ActionHandler,ActionHandler,CollapseAllHandler,DebugCommandHandler,ExpandAllHandler,FileBufferOperationHandler,MarkerViewHandler,MergeActionHandler,NewPropertySheetHandler,ShowPerspectiveHandler,ShowViewHandler,TextZoomInHandler,TextZoomOutHandler
public interface IHandlerA handler is the pluggable piece of a command that handles execution. Each command can have zero or more handlers associated with it (in general), of which only one will be active at any given moment in time. When the command is asked to execute, it will simply pass that request on to its active handler, if any.- Since:
- 3.1
- See Also:
AbstractHandler
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description voidaddHandlerListener(IHandlerListener handlerListener)Registers an instance ofIHandlerListenerto listen for changes to properties of this instance.voiddispose()Disposes of this handler.Objectexecute(ExecutionEvent event)Executes with the map of parameter values by name.booleanisEnabled()Returns whether this handler is capable of executing at this moment in time.booleanisHandled()Returns whether this handler is really capable of handling delegation.voidremoveHandlerListener(IHandlerListener handlerListener)Unregisters an instance ofIHandlerListenerlistening for changes to properties of this instance.
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Method Detail
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addHandlerListener
void addHandlerListener(IHandlerListener handlerListener)
Registers an instance ofIHandlerListenerto listen for changes to properties of this instance.- Parameters:
handlerListener- the instance to register. Must not benull. If an attempt is made to register an instance which is already registered with this instance, no operation is performed.
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dispose
void dispose()
Disposes of this handler. This method is run once when the object is no longer referenced. This can be used as an opportunity to unhook listeners from other objects.
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execute
Object execute(ExecutionEvent event) throws ExecutionException
Executes with the map of parameter values by name.- Parameters:
event- An event containing all the information about the current state of the application; must not benull.- Returns:
- the result of the execution. Reserved for future use, must be
null. - Throws:
ExecutionException- if an exception occurred during execution.
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isEnabled
boolean isEnabled()
Returns whether this handler is capable of executing at this moment in time. If the enabled state is other than true clients should also consider implementing IHandler2 so they can be notified about framework execution contexts.- Returns:
trueif the command is enabled;falseotherwise.- See Also:
IHandler2.setEnabled(Object)
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isHandled
boolean isHandled()
Returns whether this handler is really capable of handling delegation. In the case of a handler that is a composition of other handlers, this reply is intended to indicate whether the handler is truly capable of receiving delegated responsibilities at this time.- Returns:
trueif the handler is handled;falseotherwise.
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removeHandlerListener
void removeHandlerListener(IHandlerListener handlerListener)
Unregisters an instance ofIHandlerListenerlistening for changes to properties of this instance.- Parameters:
handlerListener- the instance to unregister. Must not benull. If an attempt is made to unregister an instance which is not already registered with this instance, no operation is performed.
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