Odd even number printing using thread

Question

Odd even number printing using thread.Create one thread class, two instance of the thread. One will print the odd number and the other will print the even number.

Answer 1

The same can be solved using Lock interface:

NaturalOrder.java

import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class NaturalOrder {

    public int currentNumber = 1;
    public boolean evenOdd = false;

    Lock lock = new ReentrantLock();
    Condition condition = lock.newCondition();

    public static void main(String[] args) {
        NaturalOrder naturalOrder = new NaturalOrder();
        Thread t1 = new Thread(new OddNumberLock(naturalOrder, naturalOrder.lock, naturalOrder.condition));
        Thread t2 = new Thread(new EvenNumberLock(naturalOrder, naturalOrder.lock, naturalOrder.condition));
        t1.start();
        t2.start();
    }
}

OddNumberLock.java

import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;

public class OddNumberLock implements Runnable {

    NaturalOrder naturalOrder;
    Lock lock;
    Condition condition;

    public OddNumberLock(NaturalOrder naturalOrder, Lock lock, Condition condition) {
        this.naturalOrder = naturalOrder;
        this.lock = lock;
        this.condition = condition;
    }

    @Override
    public void run() {
        lock.lock();
        while (naturalOrder.currentNumber < 20) {
            while (naturalOrder.evenOdd != false) {
                try {
                    condition.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }

            try {
                Thread.sleep(ThreadLocalRandom.current().nextInt(1000));
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            if (naturalOrder.currentNumber % 2 != 0) {
                System.out.println(naturalOrder.currentNumber);
            }
            naturalOrder.currentNumber++;
            naturalOrder.evenOdd = true;

            condition.signalAll();
        }
        lock.unlock();
    }
}

EvenNumberLock.java

import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;

public class EvenNumberLock implements Runnable {

    NaturalOrder naturalOrder;
    Lock lock;
    Condition condition;

    public EvenNumberLock(NaturalOrder naturalOrder, Lock lock, Condition condition) {
        this.naturalOrder = naturalOrder;
        this.lock = lock;
        this.condition = condition;
    }

    @Override
    public void run() {
        lock.lock();
        while (naturalOrder.currentNumber < 20) {
            while (naturalOrder.evenOdd != true) {
                try {
                    condition.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }

            try {
                Thread.sleep(ThreadLocalRandom.current().nextInt(1000));
            } catch (InterruptedException e) {
                e.printStackTrace();
            }

            if (naturalOrder.currentNumber % 2 == 0) {
                System.out.println(naturalOrder.currentNumber);
            }
            naturalOrder.currentNumber++;
            naturalOrder.evenOdd = false;
            condition.signalAll();
        }
        lock.unlock();
    }
}