Eclipse parameterized Command builder

CommandBuilder.java

/*
 * This content is released under the MIT License (http://opensource.org/licenses/MIT).
 * Copyright (c) 2014 Luca Cesari <luc@cesari.me>
 */

package lucacesari.gists;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.core.commands.Command;
import org.eclipse.core.commands.ExecutionException;
import org.eclipse.core.commands.IParameter;
import org.eclipse.core.commands.NotEnabledException;
import org.eclipse.core.commands.NotHandledException;
import org.eclipse.core.commands.Parameterization;
import org.eclipse.core.commands.ParameterizedCommand;
import org.eclipse.core.commands.common.NotDefinedException;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.commands.ICommandService;
import org.eclipse.ui.handlers.IHandlerService;

public class CommandBuilder {
    private static final Parameterization[] EMPTY_PARAMETERIZATION_ARRAY = new Parameterization[0];

    private Command command;
    private List<Parameterization> parameterizations;

    public CommandBuilder setCommand(final String commandId) throws NotDefinedException {
        final ICommandService commandService = (ICommandService) PlatformUI.getWorkbench().getService(ICommandService.class);
        command = commandService.getCommand(commandId);

        if (command == null) {
            throw new NotDefinedException("Command ID '" + commandId + "' not found.");
        }

        return this;
    }

    public CommandBuilder setParameter(final String parameterId, final String value) throws NotDefinedException {
        if (parameterizations == null && value != null) {
            parameterizations = new ArrayList<Parameterization>();
        }

        final IParameter parameter = command.getParameter(parameterId);
        final Parameterization parameterization = new Parameterization(parameter, value);
        parameterizations.add(parameterization);

        return this;
    }

    public ParameterizedCommand getCommand() {
        if (command == null) {
            return null;
        }

        if (parameterizations == null || parameterizations.isEmpty()) {
            return new ParameterizedCommand(command, null);
        } else {
            return new ParameterizedCommand(command, parameterizations.toArray(EMPTY_PARAMETERIZATION_ARRAY));
        }
    }

    public void execute() throws ExecutionException, NotDefinedException, NotEnabledException, NotHandledException {
        final ParameterizedCommand parameterizedCommand = getCommand();
        if (parameterizedCommand == null) {
            throw new ExecutionException("The command has not been configured yet.");
        }

       final IHandlerService service = (IHandlerService) PlatformUI.getWorkbench().getService(IHandlerService.class);
       service.executeCommand(parameterizedCommand, null);
    }

    public static CommandBuilder build(final String commandId) throws NotDefinedException {
        return new CommandBuilder().setCommand(commandId);
    }
}