Skip to content
C

Multithreading Programs

Multithreading can feel abstract at first — hands-on practice with simple thread examples helps make the concept concrete.

Why practice these?

Multithreading can feel abstract at first — hands-on practice with simple thread examples helps make the concept concrete.

Program 1: Two Threads Printing Simultaneously

java
class NumberPrinter extends Thread {
    public void run() {
        for (int i = 1; i <= 3; i++) {
            System.out.println(Thread.currentThread().getName() + ": " + i);
        }
    }
}

public class MultipleThreadsDemo {
    public static void main(String[] args) {
        NumberPrinter t1 = new NumberPrinter();
        NumberPrinter t2 = new NumberPrinter();
        t1.start();
        t2.start();
    }
}

Output (order may vary between runs):

Thread-0: 1
Thread-1: 1
Thread-0: 2
Thread-1: 2
Thread-0: 3
Thread-1: 3

Program 2: Using Runnable with a Lambda

java
public class RunnableLambdaDemo {
    public static void main(String[] args) {
        Runnable task = () -> System.out.println("Task executed by: " + Thread.currentThread().getName());
        Thread t = new Thread(task);
        t.start();
    }
}

Output:

Task executed by: Thread-0

Key Points to Remember

  • Thread execution order is not guaranteed — running the same program twice may show a different interleaving of output.
  • Practicing with small thread examples helps build intuition before tackling synchronization and thread pools.
  • Using lambda expressions with Runnable is a common, concise style in modern Java code.