import java.applet.Applet;
import java.awt.*;

public class Poets extends Applet {

    public void init() {
        TextArea display =
            new TextArea("", 10, 30, TextArea.SCROLLBARS_VERTICAL_ONLY);
        add(display);

        ScreenController screen = new ScreenController();
        Nursery nursery = new Nursery(display, screen);
        Revolutionary revolutionary = new Revolutionary(display, screen);
        Mowing mowing = new Mowing(display, screen);
        nursery.start();
        revolutionary.start();
        mowing.start();
    }
}

class ScreenController {

    private boolean inUse = false;

    public synchronized void askFor() {
        while (inUse)
            try {
                wait();
            }
            catch(InterruptedException e) {
                System.err.println("Exception");
            }
        inUse = true;
    }

    public synchronized void relinquish() {
        inUse = false;
        notify();
    }
}

class Mowing extends Thread {
    private TextArea display;
    private ScreenController screen; 

    public Mowing(TextArea display, ScreenController screen) {
        this.display = display;
        this.screen = screen;
    }

    public void run() {
        while (true) {
            screen.askFor();
            display.append("one man went to mow\n");
            display.append("went to mow a meadow\n\n");
            screen.relinquish();
            try {
                Thread.sleep(5000);
            }
            catch (InterruptedException e) {
                display.append ("sleep exception - design fault\n");
            }
        }
    }
}

class Nursery extends Thread {
    private TextArea display; 
    private ScreenController screen;

    public Nursery(TextArea display, ScreenController screen) {
        this.display = display;
        this.screen = screen;
    }

    public void run() {
        while (true) {
            screen.askFor();
            display.append("Mary had a little lamb\n");
            display.append("Its fleece was white as snow\n\n");
            screen.relinquish();
            try {
                Thread.sleep(5000);
            }
            catch (InterruptedException e) {
                display.append ("sleep exception - design fault\n");

            }
        }
    }
}

class Revolutionary extends Thread {
    private TextArea display; 
    private ScreenController screen;

    public Revolutionary(TextArea display, ScreenController screen) {
        this.display = display;
        this.screen = screen;
    }

    public void run() {
        while (true) {
            screen.askFor();
            display.append("Praise Marx\n");
            display.append("and pass the ammunition\n\n");
            screen.relinquish();
            try {
                Thread.sleep(5000);
            }
            catch (InterruptedException e) {
                display.append ("sleep exception - design fault\n");
            }
        }
    }
}