Re: what is the RIGHT THING to make a constructor of a subclass, using super()

From:

ram@zedat.fu-berlin.de (Stefan Ram)

Newsgroups:

comp.lang.java.programmer

Date:

28 Jul 2008 13:13:41 GMT

Message-ID:

<super-20080728145824@ram.dialup.fu-berlin.de>

Tom Anderson <twic@urchin.earth.li> writes:

public class SlashSeparatedCustomer extends Customer {
    public SlashSeparatedCustomer(String name) {
        // THIS IS ILLEGAL!
        int slash = name.indexOf('/') ;
        String first = name.substring(0, slash) ;
        String last = name.substring(slash + 1) ;
        super(first, last) ;
    }
}

  Quite complicated, and still not perfect, because it
  is not safe for multithreading or recursion (due to
  the use of static fields):

class Customer
{ public Customer
  ( final java.lang.String first, final java.lang.String last )
  {} }

class SlashSeparatedCustomer extends Customer
{
  private static java.lang.String first;
  private static java.lang.String first( final java.lang.String name )
  { if( !initialized )initialize( name ); return first; }

  private static java.lang.String last;
  private static java.lang.String last( final java.lang.String name )
  { if( !initialized )initialize( name ); return last; }

  private static boolean initialized;
  private static void initialize( final java.lang.String name )
  { if( !initialized )
    { final int slash = name.indexOf( '/' ) ;
      first = name.substring( 0, slash );
      last = name.substring( slash + 1 ); }}

  public SlashSeparatedCustomer( final java.lang.String name )
  { super( first( name ), last( name )); }}