U can use it in following structure:

ParentException : which extends Exception, and is also abstract and have an          abstract method it can be called translateException().
DataTierException : which extends ParentException, so it supposed to implement translateException method, it's would be implemented like this:
          translateException( Exception ex ){
             if ( ex instanceof Nullpointer )
                   throw new DataTierException( SpecificErrorCode )

BusinessTierException : which extends ParentException, so it supposed to implement translateException method, it's would be implemented like this:
          translateException( Exception ex ){
             if ( ex instanceof Nullpointer )
                   throw new BusinessTierException ( SpecificErrorCode )
WebTierException : which extends ParentException, so it supposed to implement translateException method, it's would be implemented like this:
          translateException( Exception ex ){
             if ( ex instanceof Nullpointer )
                   throw new WebTierException ( SpecificErrorCode )

So in each tier can be like this:

try{
    // do sth here
    DataTier.methodCall();
}catch( DataTierException ex )
{
    throw businessException.translateException( ex );
}