🚀 go-pugleaf

A vector object is a dynamic array .... you can find it in java.util.Vector

someguy <someguy@somewhere.com> wrote in message
news:958656104.72811@brs.ihug.com.au...
> i am having some difficulties with using undefined array lengths can
anyone
> help?
>
> The problem is when u declare an array u can only setits size once,
however
> i need to make the array grow larger at certain times.  I have thought of
> various ways of doing this in methods but itbecame difficult handling the
> variables due to scope issue.  So i gueess is there such a thing in java
as
> a linked list where at any point i can add or insert an element into the
> list dynamically? or do you have any other suggestions?
>
> help is appreciated.
>
>

any java.util.List implementation is. you might want to use
java.util.ArrayList (similar to Vector but not synchronized and thus faster)
or java.util.LinkedList.

-- j

"Sup" <sup@ihug.com.au> wrote in message
news:8g0r6r$hos$1@bugstomper.ihug.com.au...
> A vector object is a dynamic array .... you can find it in
java.util.Vector
>
> someguy <someguy@somewhere.com> wrote in message
> news:958656104.72811@brs.ihug.com.au...
> > i am having some difficulties with using undefined array lengths can
> anyone
> > help?
[snip]

the vector is reffered to as a "fail fast" variable type, should this be of
concern to me?
"Sup" <sup@ihug.com.au> wrote in message
news:8g0r6r$hos$1@bugstomper.ihug.com.au...
> A vector object is a dynamic array .... you can find it in
java.util.Vector
>
> someguy <someguy@somewhere.com> wrote in message
> news:958656104.72811@brs.ihug.com.au...
> > i am having some difficulties with using undefined array lengths can
> anyone
> > help?
> >
> > The problem is when u declare an array u can only setits size once,
> however
> > i need to make the array grow larger at certain times.  I have thought
of
> > various ways of doing this in methods but itbecame difficult handling
the
> > variables due to scope issue.  So i gueess is there such a thing in java
> as
> > a linked list where at any point i can add or insert an element into the
> > list dynamically? or do you have any other suggestions?
> >
> > help is appreciated.
> >
> >
>
>

someguy wrote:
> 
> what disadvantages do i have with the java.utils.ArrayList
> java.util.LinkedList not being synchronized?

don't access them from multiple threads, and you'll be fine!

On Fri, 19 May 2000 00:06:05 +1000, "someguy" <someguy@somewhere.com> wrote:

>what disadvantages do i have with the java.utils.ArrayList
>java.util.LinkedList not being synchronized?

Quoting from _The Java Class Libraries Second Edition, Volume 1
Supplement for the Java 2 Platform_ :

"java.util.ArrayList

Synchronization

The list allows more than one thread to read from it. However, if a thread
wants to modify the list, there should not be any thread reading from it at
the same time. If reads and modifications need to be able to occur
concurrently, you can create a synchronized version of the list by calling
Collections.synchronizedList() on the list. This creates a version of the
list in which all of the methods are synchronized. Note that although each
method might still need to synchronize a sequence of method calls. See the
Collections class description for more details."


Doug Lea, author of _Concurrent Programming in Java_, did much of the
initial work on the collection framework. Providing selectable concurrency
protection is one of the key features in its design.

As an aside, I really like the writeups and examples in the Java Class
Libraries books. If you have this kind of question with any frequency, they
are worthwhile books to have around.

--phil

someguy wrote:
> 
> i am having some difficulties with using undefined array lengths can anyone
> help?
> 
> The problem is when u declare an array u can only setits size once, however
> i need to make the array grow larger at certain times.  I have thought of
> various ways of doing this in methods but itbecame difficult handling the
> variables due to scope issue.  So i gueess is there such a thing in java as
> a linked list where at any point i can add or insert an element into the
> list dynamically? or do you have any other suggestions?
> 

Yes, look for java.util.Vector

If you're using Java2, you've also got other options
to choose from, including java.util.LinkedList.


-- 
<\___/>
/ O O \
\_____/  FTB.

On 18 May 2000 12:29:03 -0600, pae@dimensional.com (Phil Earnhardt)
wrote:

>On Fri, 19 May 2000 00:06:05 +1000, "someguy" <someguy@somewhere.com> wrote:
>
>>what disadvantages do i have with the java.utils.ArrayList
>>java.util.LinkedList not being synchronized?
>
>Quoting from _The Java Class Libraries Second Edition, Volume 1
>Supplement for the Java 2 Platform_ :
>
>"java.util.ArrayList
>
>Synchronization
>
>The list allows more than one thread to read from it. However, if a thread
>wants to modify the list, there should not be any thread reading from it at
>the same time. If reads and modifications need to be able to occur
>concurrently, you can create a synchronized version of the list by calling
>Collections.synchronizedList() on the list. This creates a version of the
>list in which all of the methods are synchronized. Note that although each
>method might still need to synchronize a sequence of method calls. See the
>Collections class description for more details."

I failed to mention: java.util.LinkedList works exactly the same way.

--phil

what disadvantages do i have with the java.utils.ArrayList
java.util.LinkedList not being synchronized?
"Joern W. Janneck" <janneck@NOSPAM.tik.ee.ethz.ch> wrote in message
news:3923f57c@pfaff.ethz.ch...
> any java.util.List implementation is. you might want to use
> java.util.ArrayList (similar to Vector but not synchronized and thus
faster)
> or java.util.LinkedList.
>
> -- j
>
> "Sup" <sup@ihug.com.au> wrote in message
> news:8g0r6r$hos$1@bugstomper.ihug.com.au...
> > A vector object is a dynamic array .... you can find it in
> java.util.Vector
> >
> > someguy <someguy@somewhere.com> wrote in message
> > news:958656104.72811@brs.ihug.com.au...
> > > i am having some difficulties with using undefined array lengths can
> > anyone
> > > help?
> [snip]
>
>

in JDK1.2 - use a java.util.arrayList . in Jdk1.1, use a java.util.Vector

--
--------------------------------------------------------------
http://www.users.bigpond.com/pmurray
ICQ: 26066755
"someguy" <someguy@somewhere.com> wrote in message
news:958656104.72811@brs.ihug.com.au...
> i am having some difficulties with using undefined array lengths can
anyone
> help?
>
> The problem is when u declare an array u can only setits size once,
however
> i need to make the array grow larger at certain times.  I have thought of
> various ways of doing this in methods but itbecame difficult handling the
> variables due to scope issue.  So i gueess is there such a thing in java
as
> a linked list where at any point i can add or insert an element into the
> list dynamically? or do you have any other suggestions?
>
> help is appreciated.
>
>

"someguy" <someguy@somewhere.com> wrote in message
news:958658471.384746@brs.ihug.com.au...

> the vector is reffered to as a "fail fast" variable type, should this be
of
> concern to me?

no.

-------------------------------------------------------------
http://www.users.bigpond.com/pmurray
ICQ: 26066755

"someguy" <someguy@somewhere.com> wrote in message
news:958658471.384746@brs.ihug.com.au...
> the vector is reffered to as a "fail fast" variable type, should this be
of
> concern to me?

it helps in locating bugs of the type 'you've got a live iterator on the
vector and someone changes its structure (without going through the
iterator).' can be helpful.

-- j