public class CSV2ListConverter implements Converter {    public Object getAsObject(FacesContext context, UIComponent component,       String value) throws ConverterException {    if ( context == null ) throw new NullPointerException( "context is null" );    if ( component == null ) throw new NullPointerException( "component is null");    if ( value == null ) return null;    if ( value.lastIndexOf( "," ) == -1 ){       throw new ConverterException( new FacesMessage( "CSV 文字列の変換に失敗しました。" ) );    }    String[] valueArray = value.split( "," );    List list = new ArrayList();    for (int i = 0; i < valueArray.length; i++) {       list.add( valueArray[i] );    }    return list; } public String getAsString(FacesContext context, UIComponent component,       Object value) throws ConverterException {    if ( value == null ) return "";    List list = (List)value;    StringBuffer sb = new StringBuffer();    int i = 0;    // List→ CSV 文字列    for (Iterator iter = list.iterator(); iter.hasNext();) {       sb.append( (String) iter.next() );       if ( 0 < i ) sb.append( "," );       i++;    }    return sb.toString(); }