public class Synch { private int counter; public static void main(String[] args) { Synch s = new Synch(); s.doWork(); } public void doWork() { Thread th = new Thread(() -> { for (int i = 0; i < 10000; i++) counter++; }); Thread th1 = new Thread(() -> { for (int i = 0; i < 10000; i++) counter++; }); th.start(); th1.start(); System.out.println(counter); } }