import java.util.concurrent.atomic.AtomicInteger;
public class JavaAtomic {public static void main(String[] args) throws InterruptedException {ProcessingThread pt = new ProcessingThread();Thread t1 = new Thread(pt, "t1");t1.start();Thread t2 = new Thread(pt, "t2");t2.start();t1.join();t2.join();System.out.println("Processing count=" + pt.getCount());}
}
class ProcessingThread implements Runnable {private AtomicInteger count = new AtomicInteger();@Overridepublic void run() {for (int i = 1; i < 5; i++) {processSomething(i);count.incrementAndGet();}}public int getCount() {return this.count.get();}private void processSomething(int i) {// processing some jobtry {Thread.sleep(i * 1000);} catch (InterruptedException e) {e.printStackTrace();}}
}

import java.util.concurrent.atomic.AtomicInteger;public class Main
{public static void main(String[] args){AtomicInteger atomicInteger = new AtomicInteger(100);boolean isSuccess = atomicInteger.compareAndSet(100,110); //current value 100
 System.out.println(isSuccess); //true
 isSuccess = atomicInteger.compareAndSet(100,120); //current value 110
 System.out.println(isSuccess); //false
 }
}

public class SingletonDemo {private static SingletonDemo instance = null;private SingletonDemo() { }public static synchronized SingletonDemo getInstance() {if (instance == null) {instance = new SingletonDemo ();}return instance;}
}

public class ReentrantLockTest {private static Lock fairLock = new ReentrantLock(true);private static Lock unfairLock = new ReentrantLock();@Testpublic void fair() {System.out.println("fair version");for (int i = 0; i < 5; i++) {Thread thread = new Thread(new Job(fairLock));thread.setName("" + i);thread.start();}try {Thread.sleep(5000);} catch (InterruptedException e) {e.printStackTrace();}}@Testpublic void unfair() {System.out.println("unfair version");for (int i = 0; i < 5; i++) {Thread thread = new Thread(new Job(unfairLock));thread.setName("" + i);thread.start();}try {Thread.sleep(5000);} catch (InterruptedException e) {e.printStackTrace();}}private static class Job implements Runnable {private Lock lock;public Job(Lock lock) {this.lock = lock;}@Overridepublic void run() {for (int i = 0; i < 5; i++) {lock.lock();try {System.out.println("Lock by:"+ Thread.currentThread().getName());} finally {lock.unlock();}}}}
}

//0.开始事务
begin;/begin work;/start transaction; (三者选一就可以)
//1.查询出商品信息
select status from t_goods where id=1 for update;
//2.根据商品信息生成订单
insert into t_orders (id,goods_id) values (null,1);
//3.修改商品status为2
update t_goods set status=2;
//4.提交事务
commit;/commit work;

> MULTI
OK
> INCR foo
QUEUED
> INCR bar
QUEUED
> EXEC
1) (integer) 1
2) (integer) 1