How do I allocate more RAM to Java?

Question

A java application I'm using keeps crashing, when I had a problem with a similar application I managed to fix it by allocating more of my RAM to Java. How do I do that?

(I recently upgraded to 16 GB RAM, after installing Java.)

I'm on an iMac running Mac OSX 10.6.6.

Solution

java -Xmx1024M -Xms1024M -jar *filename*.jar

Xmx is the max amount you want to allocate (in MB) and the Xms is the initial amount. You can replace the 1024 with the amount you prefer.

Comments

[Kirt]

can i change it to permanently increase the RAM given to java whenever i run call a .jar file?

[mark c]

@Bec, no, you can't do this across the board to any .jar.

[Ryan]

@Bec The only way I could think that you could do that is IDE specific. I use NetBeans and I know you can edit NetBean's config file and tell it to use more RAM. I assume you could do the same with other IDE's. But as for setting a specific amount using the command line, I believe jzd is correct.

[mickey]

Also, this is only for .JAR applications that can be run headless, without GUI. for applications that cannot, you are screwed. does JAVA have a magnificent solution for this since it cannot be set across the board (which is fairly stupid IMO for above mentioned reason...)?

[Stefan Haberl]

@MichaelTrouw not correct, you can increase memory for any Java application, regardless whether they run headless or with a GUI. Ryan's solution is JAVA's standard way to increase the memory. That said you should bear in mind that a lot of application server and IDE's come with their own config file to pass the -Xmx argument to the JVM. Check the documentation of your software vendor.