Can volatile variable be defined as static in java?

Question

Can I declare something like this??

static volatile boolean first=false;

Answer 1

Yes, you can.

A static variable in Java is stored once per class (not once per object, such as non-static variables are). This means all your objects (and static methods) share the same variable.

Declaring a variable as volatile (be it static or not) states that the variable will be accessed frequently by multiple threads. In Java, this boils down to instructing threads that they can not cache the variable's value, but will have to write back immediately after mutating so that other threads see the change. (Threads in Java are free to cache variables by default).