| # GUI Commands User Guide ## Version 2.1 |
| # Listeners and Interceptors ActionCommands support both listeners and a simple interceptor mechanism. Command listeners and notified both before and after a command is executed. Interceptors are notified before and after but have the opportunity to cancel the execution of the command. The following is an interceptor example:
       command.addInterceptor(new ActionCommandInterceptor()
       {
          public boolean beforeExecute(ActionCommand command)
          {
             // return true to continue with the command execution
             return true;
          }

          public boolean afterExecute(ActionCommand command)
          {
             ...
          }
       }
Command listeners are very similar but follow the standard event listener style as the following example shows:
       command.addCommandListener(new ActionCommandListener()
       {
          public void beforeExecute(ActionCommandEvent event)
          {
             ...
          }

          public boolean afterExecute(ActionCommandEvent event)
          {
             ...
          }
       }