src/org/ohmage/domain/campaign/Campaign.java
public void addClasses(
			final Collection<String> classIds) 
			throws DomainException {
		
		if(classIds == null) {
			throw new DomainException("The class ID list is null.");
		}
		
		classes.addAll(classIds);
	}
/**
	 * Adds a collection of classes to the already existing collection of 
	 * classes.
	 * 
	 * @param classIds The collection of class IDs to add.
	 * 
	 * @throws DomainException Thrown if the class ID list is null.
	 */
Adds a collection of classes to the already existing collection of
classes.

@param classIds The collection of class IDs to add.

@throws DomainException Thrown if the class ID list is null.
Adds a collection of classes to the already existing collection of classes . @param classIds The collection of class IDs to add . @throws DomainException Thrown if the class ID list is null .
public void addClasses(
			final Collection<String> classIds) 
			throws DomainException {
		if(classIds == null) {
			throw new DomainException("The class ID list is null.");
		}
		classes.addAll(classIds);
	}
public void addClasses ( final Collection < String > classIds ) throws DomainException { if ( classIds == null ) { throw new DomainException ( "The class ID list is null." ) ; } classes . addAll ( classIds ) ; }
Adds a collection of classes to the already existing collection of
 classes.
Adds a collection of classes to the already existing collection of classes .