wait and notifyAll

package com.karl.multithread;

public class Test {
    public static void main(String[] args) {
        Printer p = new Printer();
        Thread t1 = new NumberPrinter(p);
        Thread t2 = new LetterPrinter(p);
        t1.start();
        t2.start();
    }
}

class Printer {
    private int index = 1;
    public synchronized void print(int i) {
        while (index % 3 == 0) {
            try {
                wait();
            } catch (Exception e) {
            }
        }
        System.out.print(" " + i);
        index++;
        notifyAll();
    }

    public synchronized void print(char c) {
        while (index % 3 != 0) {
            try {
                wait();
            } catch (Exception e) {
            }
        }
        System.out.print(" " + c);
        index++;
        notifyAll();
    }
}

class NumberPrinter extends Thread {
    private Printer p;
    public NumberPrinter(Printer p) {
        this.p = p;
    }
    public void run() {
        for (int i = 1; i <= 52; i++) {
            p.print(i);
        }
    }
}

class LetterPrinter extends Thread {
    private Printer p;
    public LetterPrinter(Printer p) {
        this.p = p;
    }
    public void run() {
        for (char c = 'A'; c <= 'Z'; c++) {
            p.print(c);
        }
    }
}

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