Question

I’m writing a Java/Swing application with ~30 class my probleme is when i run my programe it load more than 150 M of the memory, is that normal ? since the application have 4 threads, parse some XML files, load some icon file, and drow some Jfreechat charts.
if not how can i do to minimize the amount of memory used by the application, is affecting some variables to null help? is loading the XML files once to use them in all the application life cycle help or i have to load them evry time i need them? is there some other tips that help me?

PS: im devlopping with a 8G memory computer in case that can affect the memory used by my program.

EDIT: it appeared that the program don’t occupy all the 150MB because i get this value from the top command on linux, by running this code in my application as vilmantas advises me:

   long free = Runtime.getRuntime().freeMemory();
   long total = Runtime.getRuntime().totalMemory();
   long max = Runtime.getRuntime().maxMemory();
   long used = total - free;

I found that he occupy much less than that (~40MB) so i decide to run it with “-Xmx40M” argument and i reduce more than 40% of memory usage in the Top command.
The problem who are occupying the rest of memory since JVM (as i know) have his own process ? and how to make this operation automatic**?** because when choosing a not appropriate value you can get a memory exception as i have by running with “-Xmx30M” argument:

   Exception in thread "Thread-2" java.lang.OutOfMemoryError: Java heap space

Answer 1

It is. This is Java, usually your VM/GC will do the job for you. Worry about memory usage when and if it becomes a problem.
If you want, there are several tools that can help you analyze what is going on. How to monitor Java memory usage?