并发挑战(一)

public class ConcurrencyTest {
    private static final long count = 10000l;

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

    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);
    }

    private static void concurrency() throws InterruptedException {
        long start = System.currentTimeMillis();//获取当前时间戳
        Thread thread = new Thread(() -> {
            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--;
        }
        long time = System.currentTimeMillis() - start;
        thread.join();//调用线程等待，只有该线程执行完成之后，才能往下执行
        System.out.println("concurrency :" + time+"ms,b="+b);
    }
}