The updated Alibaba Group Java post JD standard in 2020, the information comes from Alibaba Group’s recruitment sessions, including senior Java and technical expert positions in Tmall, Ant Financial, and middleware teams. Attached to the end of the article are the interview questions and answers for senior Java R&D positions in top Internet companies such as BATJTMD.
If you can answer 80% of the following interview questions, you can try
01 Java Post JD Standards of Major Business Departments of Ali Group
Alibaba Tmall
1. Senior JAVA engineer requires more than 3 years of JEE development experience;
2. Solid Java programming foundation, familiar with various design patterns
3. Familiar with Spring/Struts/Ibatis or other mainstream JAVA frameworks
4. Familiar with one or more of MySQL databases and have database tuning experience
5. Familiar with the entire software process, able to communicate requirements, control project progress, and have good documentation skills
6. Architects are required to have good component-level modeling capabilities, be familiar with the principles of NoSQL, MQ, Cache, and TCP/IP, and be able to design systems with complex services, high concurrency, and large data volumes
7. If none of the above meets, it doesn't matter, as long as you confirm that you are a technical talent and have enough enthusiasm for technology.
Alibaba Middleware
The Middleware Technology Department is the technical cornerstone of the Alibaba Group's ecosystem, providing reliable, efficient, and easy-to-expandable technical basic services for Taobao, Tmall, Juhuasuan, 1688, B2B, AE, and Fliggy.
skills requirement:
1. Solid programming foundation, more than 5 years of R&D and software design experience is preferred
2. Familiar with mainstream application server architecture technology system, including database and various middleware technologies (caching, messaging, etc.)
3. Familiar with system high availability and stability methods and strategies, such as disaster recovery in the same city, active live in different places, multiple live in different places, etc. Practical experience is preferred
4. Proficient in architecture design, performance optimization, fault handling, monitoring, current limiting, downgrading, plan, capacity planning actual combat experience is preferred
5. Possess good system analysis skills, good abstract thinking and logical thinking skills, and the ability to analyze and solve problems independently
Alibaba New Retail Division
1. Responsible for the architecture design and development of retail link website business products;
2. Starting from users and technology, realize future-oriented system planning, design and implementation;
3. Technical pre-research and technical difficulties to ensure system availability, stability, and scalability.
skills requirement:
1. A solid Java foundation, understanding of basic frameworks such as io, multithreading, and collections, and a certain understanding of JVM principles;
2. For the open source framework you have used, you can understand its principles and mechanisms; be familiar with Spring and ibatis open source frameworks;
3. Master multi-threaded and high-performance design, coding and performance tuning; have high concurrent application development experience;
4. Have a strong interest in technology, strong learning ability, good adaptability, strong ability to withstand pressure;
5. Technical PLA/PM who has done large-scale projects is preferred.
Ant Financial
skills requirement:
1) Bachelor degree or above, computer software or related major;
2) More than three years of actual development experience in J2EE projects; familiar with J2EE design patterns, proficient in the development of Java and Web applications;
3) Deeply understand the mechanism and code of frameworks or products in spring, ibatis, cache, mq, rpc, jvm and other fields;
4) Familiar with HBase and MySQL database applications, familiar with the high availability and performance optimization of the data layer;
5) Have a strong ability to analyze and solve problems, and have a strong sense of responsibility;
6) Have team spirit, good anti-stress ability, positive attitude, can actively integrate into the team;
7) Pay close attention to the development of the latest technology in the industry, and effectively grasp the direction of technological development;
8) Familiar with SOA, platform implementation experience, experience in large data volume, high concurrent system and large-scale website construction is preferred.
The above is the technical interview requirements for each division of Ali.
The following are the Java interview questions and answers of BATJTMD and other top Internet companies.
02 The latest summary of 2020 Alibaba Group Java post interview questions
1. What are the three parts of the java event mechanism? Introduce separately.
2. Why use thread pool?
3. What is the function of thread pool?
4. Talk about several common thread pools and usage scenarios.
5. What kinds of work queues are there in thread pools?
6. How to understand unbounded queue and bounded queue?
7. Several important parameters and process descriptions in the thread pool.
8. What is the reflection mechanism?
9. Talk about the role of reflection mechanism.
10. Will the reflection mechanism have performance problems?
11. How do you understand the http protocol?
12. Talk about the workflow of the http protocol.
13. What are the request submission methods for http?
14. What status does the 200,302,403,404,500,503 in http represent?
15. What is the difference between http get and post?
16. How do you understand cookie and session, and what are the differences?
17. What is web caching? What are the advantages?
18. What is https and how does it work?
19. What is an http proxy server and what is it for?
20. What is a virtual host and its implementation principle?
21. What is the Java virtual machine and why should I use it?
22. Talk about the life cycle and architecture of the Java virtual machine.
23. Talk about the Java memory area.
24. What is a distributed system?
25. What aspects would you consider for distributed systems?
26. Talk about the three-way handshake and four-wave handshake process of the TCP protocol.
27. Why is TCP a three-way handshake for establishing a connection protocol, but a four-way handshake for closing a connection? Why can't I connect with two handshake?
28. Why does the TCP TIME_WAIT state need to wait for 2MSL before returning to the CLOSED state?
29. What are DoS, DDoS, DRDoS attacks? How to defend?
30. Describe the Java exception hierarchy.
31. What is inspection exception, not subject to inspection exception, runtime exception? And give examples to illustrate.
32. Will the finally block be executed?
33. Under normal circumstances, when a return statement is encountered in a try block or a catch block, will the finally statement block be executed before or after the method returns?
34. The execution order of try, catch, and finally statement blocks.
35. In the Java virtual machine, how many types of data can be divided into?
36. How to understand stack and heap? What's in the heap? What is stored in the stack?
37. Why distinguish between heap and stack? Isn't it possible to store data in the stack?
38. In Java, what is the starting point of the stack and also the starting point of the program?
39. Why not put the basic types in the pile?
40. What about passing values when passing parameters in Java? Or pass by reference?
41. Is there a concept of pointer in Java?
42. In Java, what parameters are used to set the stack size?
43. How much space does an empty Object object occupy?
44. What are the types of object reference types?
45. Talk about garbage collection algorithms.
46. How to solve the problem of memory fragmentation?
47. How to solve the problems of object creation and object recycling that exist at the same time?
48. Talk about memory generation and life cycle.
49. Under what circumstances will garbage collection be triggered?
50. How to choose a suitable garbage collection algorithm?
51. Is there a limit to the maximum heap size in JVM?
52. What parameters are used to set the heap size?
53. What are the three garbage collectors for JVM?
54. Which garbage collector is preferred for throughput? Is response time a priority?
55. How to tune the JVM? What are the methods?
56. How to understand the memory leak problem? What are the circumstances that can cause memory leaks? How to solve?
57. From the perspective of distributed system deployment, what are the layers?
58. How to solve the problem of data access in the business layer?
59. In order to solve the burden of database server, how to do database distribution?
60. What is the famous Byzantine generals problem?
61. Why is the TCP/IP protocol unreliable?
62. Talk about the CAP concept.
63. How to understand strong consistency, monotonic consistency and ultimate consistency?
64. What strategies will you consider when designing distributed systems?
65. What is the most common data distribution method?
66. Talk about the consistent hash algorithm.
67. What is paxos?
68. What is the Lease mechanism?
69. How to understand the main selection algorithm?
70. Which seven-layer model does OSI have? Which four-layer model is TCP/IP?
71. How to realize the WeChat red envelope.
72. Mass data analysis.
73. Thread-safety and non-thread-safety of the test position.
74、HTTP2.0、thrift。
75. Interview telephone communication may first introduce yourself.
76. Distributed transaction consistency.
77. The underlying implementation of nio.
78. The basics of jvm must be asked, the principle of jvm GC, and how does JVM reclaim memory.
79. What is Java.
80. The difference between API interface and SDI interface (API is an interface provided to others).
81. How does dubbo make multiple calls concurrently with one link. Dubbo's principle, serialization related issues.
82. Which middleware has been used?
83. Have not done a workflow engine.
84. Previous work experience, what I think shines (Dingding)
85. Some principles of thread pools, the mechanism of locking up and down (Tmall, Ant)
86. Consider from the system level, which latitudes are distributed to consider (Tmall)
87. How to implement Hadoop bottom layer (Tmall)
88. threadLocal, thread pool, hashMap/hashTable/coccurentHashMap, etc. (Tmall)
89. Design of spike system (Tmall)
90. Virtual machine, IO related knowledge points (Tmall)
91. Linux commands (Tmall)
92. An integer array, given a number, find the sum of two numbers in the array equal to this number, and print it out. The time complexity I wrote is high and requires O(n). (Tmall)
93, n integers, find out that the sum of consecutive m numbers is the largest. (Tmall)
94. Pay more attention to open source technology (Ant Financial Shanghai)
95. The principle of database lock hiding (Ant Financial Service)
96, 1000 threads are running at the same time, how to prevent not getting stuck (air travel)
97. Parallel concurrent consumption problem (air travel)
98. How to deal with hotspots and data if high concurrency is large (Ant Financial)
99. How to get a port available on a local server
100. Issues related to flow control (Ant Financial)
101. What is the TPS of the database and whether it has been tested (Tmall)
102. What are the solutions to cache breakdown (Tmall)
103. How does Java mine the relevant principles of the collector (fortune)
104. What are the Java collections and what are their characteristics (information platform)
105. Distributed lock, redis cache, spring aop, system architecture diagram, MySQL characteristics (information platform)
106. Scenarios, pay 100,000 people at the same time, how to design a concurrent plan to ensure that all of them are sent within 1 minute. For example, a similar scenario will be proposed (information platform)
03 2020 latest BAT mandatory exam questions and answers 1. 2020 latest BAT mandatory exam questions and answers comprehensive coverage: Alibaba, Tencent, ByteDance, Baidu, Pinduoduo, JD.com, Meituan Dianping, Ele.me and other well-known Internet companies. The content includes: redis, high concurrency, multithreading, distributed, MySQL, database, thread, lock, dubbo, jvm, Java virtual machine, spring, memcached, etc.
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