package com.mutasemhajhasan.threading.example2;

/**
 *
 * @author Mutasem
 */
public class Counter {

    private int count;

    public synchronized int getCount() {
        return count;
    }


    Public synchronized void increment() throws InterruptedException {
        System.out.println("Count bfore loop: " + count);
        for (int i = 0; i < 10; i++) {
            count++;
            Thread.sleep(100);
        }
        System.out.println("Count after loop: " + count);
    }

}

package com.mutasemhajhasan.threading.example2;

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

/**
 *
 * @author Mutasem
 */
public class MyThread extends Thread {

    Counter c;

    public MyThread(Counter c) {
        this.c = c;
    }

    @Override
    public void run() {
        try {
            c.increment();
        } catch (InterruptedException ex) {
            Logger.getLogger(MyThread.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

}

package com.mutasemhajhasan.threading.example2;

/**
 *
 * @author Mutasem
 */
public class MainClass {

    public static void main(String[] args) throws InterruptedException {
        Counter c = new Counter();
        MyThread t1 = new MyThread(c);
        MyThread t2 = new MyThread(c);
        t1.start();
        Thread.sleep(200);
        System.out.println("counter " + c.getCount());
        t2.start();
        Thread.sleep(200);
        System.out.println("counter " + c.getCount());
        Thread.sleep(2000);
        System.out.println("counter " + c.getCount());

    }
}

Count bfore loop: 0
Count after loop: 10
counter 10
Count bfore loop: 10
Count after loop: 20
counter 20
counter 20