How can you print even and odd numbers in increasing order using two threads in Java?

Question

Accepted Answer

Use two threads to print even and odd numbers in increasing order.

Create two threads, one for printing even numbers and one for printing odd numbers.
Use a shared variable to keep track of the current number to be printed.
Synchronize access to the shared variable to ensure correct ordering of numbers.
Use a loop in each thread to print the next number and update the shared variable.

Accepted Answer

class NumberPrinter {
    private int num = 1;
    private final int limit;
    private final Object lock = new Object();

public NumberPrinter(int limit) {
        this.limit = limit;
    }

public void printOdd() {
        synchronized (lock) {
            while (num < limit) {
                while (num % 2 == 0) { // Wait if even number
                    try {
                        lock.wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
                System.out.println("Odd  : " + num);
                num++;
                lock.notify(); // Notify the even thread
            }
        }
    }

public void printEven() {
        synchronized (lock) {
            while (num <= limit) {
                while (num % 2 != 0) { // Wait if odd number
                    try {
                        lock.wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
                System.out.println("Even : " + num);
                num++;
                lock.notify(); // Notify the odd thread
            }
        }
    }
}

public class EvenOddThreads {
    public static void main(String[] args) {
        int limit = 10;
        NumberPrinter printer = new NumberPrinter(limit);

Thread oddThread = new Thread(printer::printOdd);
        Thread evenThread = new Thread(printer::printEven);

oddThread.start();
        evenThread.start();
    }
}

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