Liferay Remove and add UserGroup

Liferay Remove and add UserGroup.grv

import com.liferay.portal.service.*;
import com.liferay.portal.kernel.util.GetterUtil;
import com.liferay.portal.util.*;

try{
	serviceContext = new com.liferay.portal.service.ServiceContext()  
	long companyId = PortalUtil.getDefaultCompanyId()
	employee = com.liferay.portal.service.UserGroupLocalServiceUtil.getUserGroup(companyId,"EMPLOYEE");
	fired    = com.liferay.portal.service.UserGroupLocalServiceUtil.getUserGroup(companyId,"FIRED_EMPLOYEE");

	out.println(employee);
	out.println(fired);

	screenNames = "999,8888".split(",")

	for( i=0; i<screenNames.length;i++){
		screenName = screenNames[i];
		user = UserLocalServiceUtil.getUserByScreenName(companyId,screenName)
		out.println(user.getUserId());
		try{
		UserGroupLocalServiceUtil.deleteUserUserGroup(user.getUserId(),employee);
		}catch(e){out.println('DELETE:'+e)}
		try{
		UserGroupLocalServiceUtil.addUserUserGroup(user.getUserId(),fired);
		}catch(e){out.println('ADD:'+e)}
	}
 

}catch(e){
	out.println(e);
}
out.println('done');