Java programmers must---Java senior face questions [BATJ]

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A basic knowledge of:

1. Collections: List Set and comparison, comparing respective sub-classes (ArrayList, Vector, LinkedList; HashSet, TreeSet);
2. The realization of the underlying HashMap, then ask the underlying implementation of ConcurrentHashMap;
3. Sequentially storing how HashMap: refer to the underlying implementation of LinkedHashMap;
4. HashTable and ConcurrentHashMap difference;
5. String, StringBuffer and StringBuilder difference;
6. What method of Object: for example, there are methods wait, why are there;
7. Difference wait and sleep, you must understand;
8. The memory structure JVM, the JVM algorithm;
9. Strong references, cited the difference between soft and weak references;
10. How to allocate the array in memory;
11. What design pattern used, a handwriting (except single cases);
12. What is the core springmvc that the request process is how to deal, how to achieve inversion of control;
13. What is the principle spring aop is inside;
14. How mybatis result set: reflection, it is recommended to see the source code;
15. Where java multi-state performance;
16. What is the use interfaces;
17. Talk http, https protocol;
18. tcp / ip protocol stack;
19. osi five network protocol;
20. tcp, udp difference;
21. What used encryption algorithms: symmetric encryption, asymmetric encryption algorithm;
22. Tcp talk about the three-way handshake, waving four times;
23. The difference between cookie and session, distributed environment how to save the user state;
24. git, svn difference;
25. Please write a stack overflow, heap overflow in the code;
26. ThreadLocal it can be used to share data;

Second IO:

1. bio, nio, aio difference;
2. nio framework: dubbo implementation principle;
3. Jingdong internal communications protocol jsf What to use: See the protocol dubbo;

Three algorithms:

1. java heap and stack often said, what are the data structure; In addition, why is divided into the heap and stack to store data.
2. How to insert data TreeMap: binary tree l, d, ambidextrous;
3. After a sorted array, insert data, what methods can be used? A: The dichotomy; Q: How much time complexity?
4. 平衡二叉树的时间复杂度；
5. Hash算法和二叉树算法分别什么时候用；

四. 多线程相关：

1. 说说阻塞队列的实现：可以参考ArrayBlockingQueue的底层实现（锁和同步都行）；
2. 进程通讯的方式：消息队列，共享内存，信号量，socket通讯等；
3. 用过并发包的哪些类；
4. 什么地方用了多线程；
5. Excutors可以产生哪些线程池；
6. 为什么要用线程池；
7. volatile关键字的用法：使多线程中的变量可见；

五. 数据库相关（mysql）：

1. msyql优化经验：
2. mysql的语句优化，使用什么工具；
3. mysql的索引分类：B+，hash；什么情况用什么索引；
4. mysql的存储引擎有哪些，区别是什么；
5. 说说事务的特性和隔离级别；
6. 悲观锁和乐观锁的区别，怎么实现；

六. mq：

1. mq的原理是什么：有点大。。都可以说；
2. mq如何保证实时性；
3. mq的持久化是怎么做的；

七. nosql相关（主要是redis）:

1. redis和memcache的区别；
2. 用redis做过什么；
3. redis是如何持久化的：rdb和aof；
4. redis集群如何同步；
5. redis的数据添加过程是怎样的：哈希槽；
6. redis的淘汰策略有哪些；
7. redis有哪些数据结构；

八. zookeeper:

1. zookeeper是什么；
2. zookeeper哪里用到；
3. zookeeper的选主过程；
4. zookeeper集群之间如何通讯；
5. 你们的zookeeper的节点加密是用的什么方式；
6. 分布式锁的实现过程；

九. linux相关：

1. linux常用的命令有哪些；
2. 如何获取java进程的pid；
3. 如何获取某个进程的网络端口号；
4. 如何实时打印日志；
5. 如何统计某个字符串行数；

十. 设计与思想：

1. 重构过代码没有？说说经验；
2. 一千万的用户实时排名如何实现；
3. 五万人并发抢票怎么实现；