EarlyNotify.java Source code

Introduction

Here is the source code for EarlyNotify.java

Source

import java.util.Collections;
import java.util.LinkedList;
import java.util.List;

public class EarlyNotify extends Object {
    private List list;

    public EarlyNotify() {
        list = Collections.synchronizedList(new LinkedList());
    }

    public String removeItem() throws InterruptedException {
        synchronized (list) {
            while (list.isEmpty()) {
                print("wait()");
                list.wait();
                print("done with wait()");
            }
            String item = (String) list.remove(0);

            return item;
        }
    }

    public void addItem(String item) {
        print("entering");
        synchronized (list) {
            list.add(item);
            print("added: '" + item + "'");

            list.notifyAll();
            print("notified");
        }
        print("leaving");
    }

    private static void print(String msg) {
        String name = Thread.currentThread().getName();
        System.out.println(name + ": " + msg);
    }

    public static void main(String[] args) {
        final EarlyNotify enf = new EarlyNotify();

        Runnable runA = new Runnable() {
            public void run() {
                try {
                    String item = enf.removeItem();
                    print("returned: '" + item + "'");
                } catch (InterruptedException ix) {
                    print("interrupted!");
                } catch (Exception x) {
                    print("threw an Exception!!!\n" + x);
                }
            }
        };

        Runnable runB = new Runnable() {
            public void run() {
                enf.addItem("Hello!");
            }
        };

        try {
            Thread threadA1 = new Thread(runA, "A");
            threadA1.start();

            Thread.sleep(500);

            Thread threadA2 = new Thread(runA, "B");
            threadA2.start();

            Thread.sleep(500);

            Thread threadB = new Thread(runB, "C");
            threadB.start();

            Thread.sleep(1000);

            threadA1.interrupt();
            threadA2.interrupt();
        } catch (InterruptedException x) {
        }
    }
}