Example to learn about wait and notify in Thread

ThreadWaitAndNotifyDemo_Message.java

package ThreadWaitAndNotifyDemo;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Message {
    String mesg;
    boolean received =false;
    synchronized void readmesg(){
        try{
            try{
                while(received){
                    wait();
                }
            }
            catch(InterruptedException ex){
                System.out.println("Thread interrupted while waiting");
            }
            InputStreamReader ins = new InputStreamReader(System.in);
            BufferedReader br = new BufferedReader(ins);
            System.out.print("Type in a message: ");
            mesg = br.readLine();
        }
        catch(IOException ex){
            System.out.println("IO Error");
        }
        received=true;
        notify();
    }
    synchronized void printmsg(){
        try{
            while(!received){
                wait();
            }
        }
        catch(InterruptedException ex){
            System.out.println("Thread interrupted while waiting");
        }
        System.out.println("The received message is: " + mesg);
        received=false;
        notify();
    }
}

ThreadWaitAndNotifyDemo_Print.java

package ThreadWaitAndNotifyDemo;

public class Print implements  Runnable {
    Message ms;
    Thread th;
    Print(Message ms){
        this.ms = ms;
        th  = new Thread(this);
        th.start();

    }
    @Override
    public void run() {
        ms.printmsg();
    }
}

ThreadWaitAndNotifyDemo_Receive.java

package ThreadWaitAndNotifyDemo;

public class Receive implements Runnable {
    Message ms;
    Thread th;
    Receive(Message ms){
        this.ms = ms;
        th= new Thread(this);
        th.start();;
    }
    @Override
    public void run() {
        ms.readmesg();
    }
}

ThreadWaitAndNotifyDemo_ThreadDemo.java

package ThreadWaitAndNotifyDemo;
/*
 * Learning reference:
 * Book: Programming in JAVA2
 * Dr. K. Somasundaram
 * */

public class ThreadDemo {
    public static void main(String[] args) {
        Message ms = new Message();
        for (int i = 0; i < 3; i++) {
            new Print(ms);
            new Receive(ms);
        }
    }
}

Sample output

Type in a message: Hello
The received message is: Hello
Type in a message: How are you?
The received message is: How are you?
Type in a message: Thanks
The received message is: Thanks

Example on producer and consumer