CODEWITHSUNDEEP
javastaticbehavior
AZ_
AZ_

Reputation: 21899

Static String conundrum mystery behaviour

I have two classes. class Test and class Application. Test class implements Runnable and is a thread..of course.

Both classes have public static void main.

First:

First I launch the Test class in which there is a class level variable "a"

public static String a = "abc";

That points to a string object and Inside the Thread I am just assigning it a new value and printing that value.

Secondly:

I launch my Application class that also have a main method and I just printed the Static String in class Test and surprisingly it prints "abc". Please note that I launched the second class after starting of my Test class. Ideally it should print NULL as because of Java Sandbox in which every process runs and one process should not access other process.

Now my question is why ? Why it shouldn't printed the new assigned String. I am giving both classes below

import java.util.Date;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 *
 * @author AZ
 */
public class Test implements Runnable {

   public static String a = "abc";


    @Override
   public void run(){

        while(true){
           System.out.println(a); 
           a = new Date().toString();
           try {
               Thread.sleep(2000);
           } catch (InterruptedException ex) {
               Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex);
           }
        }      
   }
}
class ThreadRunner {
   static public void main(String args[]){
       new Thread(new Test()).start();
   }
}

Second Class

import com.springhibernate.beans.MessageBean;
import com.springhibernate.beans.Test;
import org.springframework.beans.factory.annotation.Autowired;

/**
 *
 * @author AZ
 */
public class Application {


    public static void main(String args[]){


         System.out.println("Test of printing String " + Test.a);

    }
}

Upvotes: 0

Views: 78

Answers (1)

SLaks
SLaks

Reputation: 887459

Each process has its own copy of the static field.

However, each process also runs the class intializer, so each copy of the field is intialized to abc.

Upvotes: 3

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