public HTML addClasses(final String...classtypes) {
		if ( classtypes == null )
			return this;
		
		final String classesAsString = this.getOrCreateAttr("class");
		final List<String> classesAsArray = new ArrayList<String>( );
		
		for (final String s : classesAsString.split(" "))
			classesAsArray.add(s);
		
		for (final String classtype : classtypes) {
			boolean duplicated = false;
			for (final String sClass : classesAsArray)
				if ( classtype.equals(sClass) )
					duplicated = true;
			
			if ( !duplicated )
				classesAsArray.add(classtype);
		}
		
		if ( classesAsArray.size( ) > 0 ) {
			final StringBuilder sb = new StringBuilder( );
			sb.append(classesAsArray.get(0));
			
			for (int i = 1; i < classesAsArray.size( ); i++) {
				sb.append(classesAsArray.get(i));
				
				if ( !(i == classesAsArray.size( ) - 1) )
					sb.append(" ");
			}
			
			this.attr.put("class", sb.toString( ));
		}
		
		return this;
	}