public class ConcurrencyTest {

    private static final long count = 10001;

    public static void main(String[] args) throws InterruptedException {
        concurrency();
        serial();
    }

    private static void concurrency() throws InterruptedException{
        Long start = System.currentTimeMillis();
        Thread thread = new Thread(new Runnable() {
            @Override
            public void run() {
                int a = 0;
                for (long i = 0; i < count; i++) {
                    a += 5;
                }
            }
        });

        thread.start();
        int b = 0;
        for (long i = 0; i < count; i++) {
            b--;
        }
        thread.join();
        long time = System.currentTimeMillis() - start;
        System.out.println("concurrency:" + time + "ms, b = " + b);
    }

    private static void serial(){
        long start = System.currentTimeMillis();
        int a = 0;
        for (long i = 0; i < count; i++) {
            a += 5;
        }
        int b = 0;
        for (long i = 0; i < count; i++) {
            b--;
        }
        long time = System.currentTimeMillis() - start;
        System.out.println("serial:" + time + "ms, b = " + b + ", a=" + a);
    }
}

public class DeadLockDemo {
    
    private static String A = "A";
    private static String B = "B";

    public static void main(String[] args) {
        new DeadLockDemo().deadLock();
    }
    
    private void deadLock(){
        Thread thread1 = new Thread(new Runnable() {
            @Override
            public void run() {
                synchronized (A){
                    try {
                        Thread.sleep(2000);
                    } catch (InterruptedException e){
                        e.printStackTrace();
                    }
                    synchronized (B){
                        System.out.println("1");
                    }
                }
            }
        });

        Thread thread2 = new Thread(new Runnable() {
            @Override
            public void run() {
                synchronized (B){
                    synchronized (A){
                        System.out.println("2");
                    }
                }
            }
        });
        thread1.start();
        thread2.start();
    }
}