A simple deadlock demo application

DeadlockDemo.java

class DeadlockDemo {
    private static final Object lock1 = new Object();
    private static final Object lock2 = new Object();
    private static final Object lock3 = new Object();
    private static final Object lock4 = new Object();
    
    public static void main(String[] args) throws InterruptedException {
        // Create deadlock threads
        Thread deadlock1 = new Thread(() -> {
            synchronized (lock1) {
                System.out.println("Thread 1: Holding lock1...");
                try { Thread.sleep(100); } catch (InterruptedException e) {}
                System.out.println("Thread 1: Waiting for lock2...");
                synchronized (lock2) {
                    System.out.println("Thread 1: Acquired lock2");
                }
            }
        }, "DeadlockThread-1");
        
        Thread deadlock2 = new Thread(() -> {
            synchronized (lock2) {
                System.out.println("Thread 2: Holding lock2...");
                try { Thread.sleep(100); } catch (InterruptedException e) {}
                System.out.println("Thread 2: Waiting for lock1...");
                synchronized (lock1) {
                    System.out.println("Thread 2: Acquired lock1");
                }
            }
        }, "DeadlockThread-2");
        
        // Create second deadlock with different locks
        Thread deadlock3 = new Thread(() -> {
            synchronized (lock3) {
                System.out.println("Thread 3: Holding lock3...");
                try { Thread.sleep(100); } catch (InterruptedException e) {}
                System.out.println("Thread 3: Waiting for lock4...");
                synchronized (lock4) {
                    System.out.println("Thread 3: Acquired lock4");
                }
            }
        }, "DeadlockThread-3");
        
        Thread deadlock4 = new Thread(() -> {
            synchronized (lock4) {
                System.out.println("Thread 4: Holding lock4...");
                try { Thread.sleep(100); } catch (InterruptedException e) {}
                System.out.println("Thread 4: Waiting for lock3...");
                synchronized (lock3) {
                    System.out.println("Thread 4: Acquired lock3");
                }
            }
        }, "DeadlockThread-4");
        
        // Start all deadlock threads
        deadlock1.start();
        deadlock2.start();
        deadlock3.start();
        deadlock4.start();
        
        deadlock1.join();
        deadlock2.join();
        deadlock3.join();
        deadlock4.join();
        System.out.println("All threads started. Deadlocks will occur shortly...");
    }
}