Question

I am thinking about how much a class resides in memory in case it is not being accessed by other objects in memory?

for example suppose I have some class like this:

public class OrderNumber {
 private static long counter = 0;

 public static long getOrderNumber(){
          if (counter >= 100) {
            return counter = 1;
          }
          return ++counter;
 }
}

And I call its static method from another class:

long number = OrderNumber.getOrderNumber(); 

each time I call it, it returns an incremental number, 1, 2, 3, 4, …

So, My question is What is the probability of this method to return the initial value where it is supposed to return the sequenced value ??

Answer 1

Right now, the answer is forever. Class definitions are put into the permanent generation, and remain there until the program terminates.

Note, this is a problem for dynamic languages on the JVM, like JRuby, which create classes on the fly, because these classes waste space. I believe there are changes in the works that will resolve this problem – for example, the G1 collector