Re: Creation of collection objects in a loop

From:

Lew <lew@lewscanon.com>

Newsgroups:

comp.lang.java.help

Date:

Fri, 18 Jul 2008 11:34:01 -0700 (PDT)

Message-ID:

<c96c434e-15b0-45c4-998b-5939f8f86d81@m36g2000hse.googlegroups.com>

Hendrik Maryns wrote:

List<Record> records = new ArrayList<Record>();
for (from beginning to the end of text file) {
Record record = new Record( gatherData );
records.add(record);
}

Daniel Moyne wrote:

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 yo=

keep using the same name "record" ?

The first record is pointed to from within the List. The variable
'record' now points to a new instance.

Review the Java tutorial on the Sun Java site.

Remember that a variable is not an object. A (reference) variable is
a pointer to an object. You can simply point it to a different object
at any time.

This is a vitally important point to assimilate if you are going to
use Java successfully. It influences things like garbage collection
(GC) and whether you get memory leaks (actually packratting, but Java
folks refer to that as "leaking" anyway).

A variable is not an object, it is a pointer to an object. It can
point to different objects at different times. That is why the
attempt to dereference a variable that points to null results in what
is called a NullPointerException.

--
Lew