Exam LAb Threads Problem-2

[Mohit G Gupta]

 public class ThreadClass extends Thread{

     public ThreadClass(int x){
          this.x=x;
     }

     static String s="";
     static volatile int x=0;

     public static void doVIP(){
          s=s+x;
          try{
               Thread.sleep(10);
          }catch(Exception e){
               s=s+x;
          }
     }

     public void run(){
          synchronized(s){
               doVIP();
          }
     }

     public static void doDelay(long g){
          try{Thread.sleep(g);}catch(Exception e){}
     }

     public static void main(String args[]){

          ThreadClass tc1=new ThreadClass(2);
          ThreadClass tc2=new ThreadClass(1);
          ThreadClass tc3=new ThreadClass(0);

          tc1.start(); doDelay(100); System.out.print(s);
          tc2.start(); doDelay(100); System.out.print(s);
          tc3.start(); doDelay(100); System.out.print(s);

     }
}   

In the exam lab explanation ,it's written that doVIP would be called 3 times by each thread
the output is:
000000

i cannot get how is this output occuring ..
iand each thread is assigning it's own value ti
static volatile int x=0;
how is all zero's possible in output ?

[Rohit Ramachandran]

Omg, is volatile even there in the syllabus? I don't remember seeing it in Kathy Sierra and Bert Bates.

[Ankit Garg]

x is static, so every instance of the class will share its value. Since the last constructor call will set the value of x to 0, so the output will contain only 0s.

Rohit, volatile is very simple, it just tells the JVM that the variable's value changes very frequently so JVM should not cache the value of this variable...