JD & Huawei Java development classic questions over the years

This series plans to collect hundreds of interviews from friends and readers. The author's collection is convenient for viewing. If you have interviews, please contact me.

This series is still far from the end. It will be updated to cover all the positions of all first-line manufacturers. You can also pay attention to it.

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Huawei:

(1) Topological sorting ideas
(2), the time complexity and advantages and disadvantages of other commonly used sorts
(3), several types and principles of operating system IO
(4), nginx event processing model
(5), how does android prevent processes Being killed
(6), Volley framework principle
(7), how to clean up the application cache
(8), the difference between pull, sarx, and dom parsers
(9), java class loading mechanism
(10), java garbage collection algorithm
(11) , Http message format
(12), the difference between http and https
(13), how to encrypt transmission between server and app
(14), design an xml format, serialize a class to xml
(15), introduce asymmetric encryption
(16), introduce the principle of three-level cache
(17), how to maintain long connections
(18), talk about the understanding of spring ioc, aop, etc.
(19), android hot loading
(20), android memory model
21, hashtable and hashmap
22, the difference between wait() and sleep()

Jingdong:

(1) Advantages of Java
(2) Write a singleton pattern.
(3) Write SQL statements according to the following table. Count how many subjects each student has scores greater than 80 points.
Name fraction of course
the Name Score Course,
(4), talk about the GC algorithm.
(5) How to detect deadlock.
(6), talk about the ThreadLocal keyword.
(7) The difference between clustered index and non-clustered index.
(8), talk about the specific use of Spring's IOC and AOP in the project.
(9), talk about the understanding of database affairs.
(10) Algorithm implementation questions, the interviewer will ask questions based on the problems encountered in the actual development process.
Topic: When  
we shop at JD, the payment link will choose the payment method, which is mainly divided into two types: cash and electronic payment, and then add custom to ensure that the above is cash coupons and the bottom is electronic payment. For
example: voucher and red envelope are all cash; WeChat , Alipay and bank cards are all electronic payments; suppose you add a cash payment method now, after adding it, ensure
  that the upper part is a cash coupon and the lower part is an electronic payment.
Name Number
Voucher 1
Red envelope 2
WeChat 3
Alipay 4
Bank card 5
(11) The generation strategy of Hibernate.
(12), talk about struts.
(13) Are you familiar with mysql? Do you know the gap lock?
(14), String, StringBuffer, StringBuilder immutability
(15), have you used any collections?
(16) How does Arraylist realize sorting?
(17) Have you ever understood the front end?
(18) Do you use too many threads? Introduce several thread states
(19), the difference between wait and sleep
(20), Git
(21), associated SQL queries
(22), design patterns
(23), how to implement Spring's annotations?
(24) How does Redis solve key conflicts
(25), scenario simulations give solutions
(26), what Java technology has been used
(27), what technology do you think you know the most? What is the most time spent?
(28) Do you understand Spring? How did you learn it? Have you ever read the source code?
(29) Have you had a deep understanding of redis?
(30) What are the Thread statuses?
(31), the difference between Synchronized and lock
(32), the difference between general thread and daemon thread
(33), the four isolation levels of database transactions, which level is MySql at?
(34) Which of the JDK embodies the command mode?
(35) What design pattern does the thread pool use?
(36) What are the general considerations when using thread pools?
(37) Principle of Consistency Hash
(38) How does the school oj platform project achieve 1000 people concurrency? Where is the performance bottleneck of concurrency?