Re: Creation of collection objects in a loop

From:

Patricia Shanahan <pats@acm.org>

Newsgroups:

comp.lang.java.help

Date:

Fri, 18 Jul 2008 12:07:30 -0700

Message-ID:

<g5qplk$t9f$1@ihnp4.ucsd.edu>

Daniel Moyne wrote:

Hendrik Maryns wrote:

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GArlington schreef:
| On Jul 18, 2:33 pm, Daniel Moyne <daniel.mo...@neuf.fr> wrote:
|> This question is really generic ; I know how to read information from a
|> file ; from this file I want to display built object that I will name
|> in this post "record" ; so I will have a class "Record" ; so it will be
|> something like this :
|> for (from beginning to the end of text file) {
|> (a) gathering of "data" from file for generic record;
|> (b) Record record(i) = new Record(data);
|> (c) addition of record(i) into panel for display;
|> i+=1;
|>
|> }
|>
|> I know ho to handle (a) and (c) but how to create my collection of
objects
|> record(i) (meaning name of instance to be changed at each i iteration)
|> as the name of an object is supposed to be "fixed" ; I have the strong
feeling
|> that my question is entirely ridiculous but I have to go to the bottom
|> of it.
|>
|> Thanks.
|
| You know how to do a), you know how to do c), but you do not know how
| to initialise your own class Record with the data you just read???

List<Record> records = new ArrayList<Record>();
|> for (from beginning to the end of text file) {
|> (a) gathering of "data" from file for generic record;
~ Record record = new Record(data);
~ records.add(record);
|> (c) addition of record(i) into panel for display;
|> }

....

ok Hendrik you propose a List to store my instances but at the first
iteration you do :
Record record = new Record(data1);
at the second iteration you do :
Record record = new Record(data2);
then with this what happens to the first instanciated object record as you
keep using the same name "record" ?

Nothing at all happens to the first instantiated Record object. It is
still reachable, e.g. as records.get(0), so it cannot be garbage collected.

You are not responsible for keeping a direct reference to each Record
you still need. The JVM is responsible for preserving each object that
can be reached by any continuing calculation in any active thread.

If you wanted that first instantiated Record to go away you would have
to either remove it from the List referenced by records, or change
records so that it no longer points to that particular List.

Patricia