Java declare persistent static variable

Question

I have a class and I need to create a unique counter within that, something like that:

public class Foo {
    private static int FOO_COUNT = 0

    public static getNextCount(){
        return ++FOO_COUNT;
    }
    //... more methods...
}

The counter value has to be persistent between Java VM restarts, app re-deployment etc, so that provides continuous counter throughout application life-cycle.

How (and if) that could be achieved (preferably without resorting to the DB or similar persistence mechanisms)?

Answer 1

You need to serialize your object and after you can save it localy like this for example :

  import java.io.*;
    public class SerializeDemo {

       public static void main(String [] args) {
          private static int FOO_COUNT = 0;

          try {
             FileOutputStream fileOut =
             new FileOutputStream("/tmp/save.ser");
             ObjectOutputStream out = new ObjectOutputStream(fileOut);
             out.writeObject(FOO_COUNT);
             out.close();
             fileOut.close();
             System.out.printf("Serialized data is saved in /tmp/save.ser");
          } catch (IOException i) {
             i.printStackTrace();
          }
       }
    }


    public class Foo  implements java.io.Serializable  {
        private static int FOO_COUNT = 0

        public static getNextCount(){
            return ++FOO_COUNT;
        }
        //... more methods...
    }