Synchoronizing a static method

[Anand Sidharth]

Synchoronizing a static method
public class A
{
public static synchronized void m1()
{
System.out.println("method1");
//some code here
}
public synchronized void m2()
{
System.out.println("method2");
//some code here
}
public static void main(String[] args)
{
A a = new A();
a.m2();
a.m1();
A b = new B();
b.m2();
b.m1();
}
}
??In the above code the static method m1 and non-static method m2 are synchronized.
I just need to know how a lock will be gained by a Thread calling method m1 since it is static and common to all instances.
Thanks in advance.

[karl koch]

hi
from the api documentation of java.lang.Object:

getClass
public final Class getClass()
Returns the runtime class of an object. That Class object is the object that is locked by static synchronized methods of the represented class.
Returns:
the object of type Class that represents the runtime class of the object.
hashCode

cheers
karl

[Ko Ko Naing]

Originally posted by Anand Sidharth:
I just need to know how a lock will be gained by a Thread calling method m1 since it is static and common to all instances.
Thanks in advance.

The behavior of the Threads are unpredictable and they are managed by JVM to gain a lock... The algorithm is behind the scence...

[Pradeep bhatt]

Every class has a class Object. When a static method is synchronized it means that the thread must obtain lock on the class Object.

[Ko Ko Naing]

Originally posted by Pradeep Bhat:
Every class has a class Object.

I'm not that sure what u mean by that... Do u mean "Every class is a class Object."
Correct me, if I'm wrong...

[Ilja Preuss]

Originally posted by Ko Ko Naing:

I'm not that sure what u mean by that... Do u mean "Every class is a class Object."
Correct me, if I'm wrong...

Well, you would be correct if it were Smalltalk...
In Java, classes are *not* objects, but are associated to objects of the type java.lang.Class, which just hold meta data about the actual class.
One place where this difference becomes apparent is in class methods (static methods) not being polymorphic.