Chat Multi-Thread Using wait and Notify

Chat.java

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package waitnotifyexample;

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

/**
 *
 * @author toraj
 */
public class Main {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here
        System.out.println("startinggggggggggggggggggg");
         Chat m = new Chat();
        T1 t1 = new T1(m);
        T2 t2 = new T2(m);
//        try {
//            t1.join();
//            t2.join();
//
////        Thread.dumpStack();
//        } catch (InterruptedException ex) {
//            Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
//        }
//        System.out.println("end of main");
        
//        Thread.dumpStack();
    }

}

class Chat {
    boolean flag = false;

    public synchronized void Question(String msg) {
        if (flag) {
            try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        System.out.println(msg);
        flag = true;
        notify();
    }

    public synchronized void Answer(String msg) {
        if (!flag) {
            try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

        System.out.println(msg);
        flag = false;
        notify();
    }
}

class T1 extends Thread {
    Chat m;
    String[] s1 = { "Hiq", "How are you ?", "I am also doing fine!" };

    public T1(Chat m1) {
        this.m = m1;
        new Thread(this, "Question").start();
    }

    public void run() {
        for (int i = 0; i < s1.length; i++) {
            m.Question(s1[i]);
        }
//        System.out.println("q finished");
    }
}

class T2 extends Thread {
    Chat m;
    String[] s2 = { "Hi", "I am good, what about you?", "Great!" };

    public T2(Chat m2) {
        this.m = m2;
        new Thread(this, "Answer").start();
    }

    public void run() {
        for (int i = 0; i < s2.length; i++) {
            m.Answer(s2[i]);
        }
//        System.out.println("a finished");
    }
}