some question about static methods and Thread safety , please

[raminaa niilian]

Hi
Thank you for reading my post.
1-Are static methods thread safe ? I mean if i declare a method to be static , will it run in guarded mode ?
2-if static methods are thread safe , does JVM run them internally in Synchronized mode?

by static method i mean :

public static int DoSomeOp()
{
return 10;
}

Thank you

[Ulf Dittmer]

Static-ness and thread safety are unrelated concepts. The JVM runs them in synchronized mode only if they're declared to be synchronized, or part of a synchronized block. So a static method needs to take the same precautions a non-static method would take against concurrent access problems.

[Stan James]

In general what makes something unsafe is two threads locking or modifying a shared resource like an object, file, database or partner system. Your method didn't do that, so it's ok for now.

You could have a shared resource as a static varible, a parameter, a member variable on a singleton, anything you get from another method, anything you give to another method or something external to your code. I bet there are more ways I didn't think of just now. All this can make maintaining thread safety kind of tricky!

[Jeff Albertson]

raminaa,

Are you aware that static methods can be modified by the keyword "synchronized", and that the following two ways of making a static method synchronized are equivalent?

public class Test {
...
public static synchronized void f() {
...
}
public static void f() {
synchronized(Test.class) {
...
}
}
}