Dynamic Array Resizing

[kris reddy]

I have a class with some data members in it. Data for the objects comes frm a XML file. I have to parse out the xml file and create objects. Before reading the XML file i dunno as to how many objects i need to create. I wud like to know a way where I can dynamically increase the size of the object array as I read through the XMl file.
Thanks in advance,
Kris.

[Dirk Schreckmann]

Once created, the length of arrays in Java cannot be changed. You may want to consider using a collection. Take a look at the four part series of articles on Java collections by Thomas Paul. They can be found in the past four JavaRanch newsletters. And take a look at the coverage of Java collections in Sun's Java Tutorial (their tutorial site is down at the moment, otherwise I'd give you a link).

[Michael Morris]

Hi kris,
Use a java.util.ArrayList. You can do something like this:

  ArrayList dynamicArray = new ArrayList();
   // Iterate thru the XML data
    ...
    dynamicArray.add(xMLObject);
    ...
    Object[] staticArray = dynamicArray.toArray();

The staticArray will contain all of your XML objects in the correct order.
Hope this helps,
Michael Morris

[kris reddy]

When using a ArrayList, does the ArrayList dynamically allocate some memory for the object being stored or does it reference the address of the object location. I would like to know what happens internally.
Chill,
kris

[Ron Newman]

If you're concerned about performance, take a look at the ensureCapacity() method and the one-argument constructor, which takes an "initialCapacity" argument.

[kris reddy]

well my question is about the type of storage in an ArrayList. I understand that ensureCapacity operation dynamically reduces the amount of incremental reallocation.
Take it Ezy Ron,
kris

[Dirk Schreckmann]

An Object array is used internally.
You can look at the source code for the java.util.ArrayList and much of the J2SE. Perhaps your installation of the JDK has a file called src.jar or src.zip in the root directory. Just unzip it and take a look.