Creating & Running Threads

// Method 1: Extend Thread class
class DownloadThread extends Thread {
    private String fileName;
    
    DownloadThread(String fileName) {
        this.fileName = fileName;
    }
    
    @Override
    public void run() {
        System.out.println("Downloading " + fileName + "...");
        try {
            Thread.sleep(2000);  // Simulate download time
        } catch (InterruptedException e) {
            System.out.println("Download interrupted!");
        }
        System.out.println(fileName + " downloaded!");
    }
}

// Method 2: Implement Runnable (preferred)
class PrintTask implements Runnable {
    private String taskName;
    private int count;
    
    PrintTask(String taskName, int count) {
        this.taskName = taskName;
        this.count = count;
    }
    
    @Override
    public void run() {
        for (int i = 1; i <= count; i++) {
            System.out.println(taskName + ": Step " + i + "/" + count);
            try {
                Thread.sleep(500);
            } catch (InterruptedException e) {
                return;
            }
        }
        System.out.println(taskName + " completed!");
    }
}

public class ThreadDemo {
    public static void main(String[] args) throws InterruptedException {
        System.out.println("=== Starting Downloads ===");
        
        // Create and start threads
        DownloadThread d1 = new DownloadThread("image.jpg");
        DownloadThread d2 = new DownloadThread("video.mp4");
        Thread t3 = new Thread(new PrintTask("Analysis", 3));
        
        d1.start();  // start(), not run()!
        d2.start();
        t3.start();
        
        // Wait for all threads to finish
        d1.join();
        d2.join();
        t3.join();
        
        System.out.println("\nAll tasks completed!");
        
        // Lambda syntax (Java 8+)
        Thread quickTask = new Thread(() -> {
            System.out.println("Quick task running on " + Thread.currentThread().getName());
        });
        quickTask.start();
    }
}