Introduction : graduated more than two years, has been engaged in the development aspects of the java web, feel a little bit into the count threshold bar to record the growth of their own right, the majority of users who want to give some reference, and common progress. Part of the problem is the following interview asked, summed up some of their own learning to master the knowledge, not been asked, but still want to know, not for the interview and the interview, this knowledge still need to understand learning.
1. LinkedList and Arraylist difference? LinkedList whether analog or stack queue?
2. HashMap and HashTable difference?
3. talk about the process put the HashMap? how key values calculated? How to reduce hash conflicts? Why after the condition becomes red-black tree? It is thread-safe, what happens?
4. HashMap unsafe, then it is to replace it with what? Simply put, under the principle of? ConcurrentHashMap structural changes (e.g.: segement -> cas + synchronized)
5. synchronized and voliate the difference? Reentrant lock know? AQS have to understand it?
6. Thread in several states, starting what way? What are the thread pool parameters, and interpret? Talk about understanding the thread pool are there? Why not create a thread pool with Executors it? What is the thread pool to abandon the policy?
7. ThreadLocal have not been used, the use of the place, what does? What is the principle? What map of the key and value are saved?
8. mysql default transaction level? Explain the difference between other levels, what will happen simultaneously example
9. Innodb and Myisam difference? Clustered index and non-clustered index difference and so on, sql tuning, the leftmost matching principle? What is back to the table? How to avoid full table scan?
10. What situation will lead to failure @Transaction
11. The handwriting heap overflow stack overflow demo
12. Interface Idempotence how to achieve?
13.redis data types, deployment? (You might be asking yourself have not deployed, for example:? Cluster or master and slave, how to configure)
14.redis general purpose, distributed lock, data caching, asynchronous message queues, respectively how to achieve?
15. The database level how to solve the competition problems in data concurrency scenarios? That level of code it?
16. The sub-libraries have done it? Then you do not have to find out about it? How to do it?
17.spring IOC. AOP: spring default which aop, difference between the two agents? aop concept
The principle of 18.mybatis (not asked before, still need to know)
19. The hand-drawn project architecture?
20. (algorithm) reversed handwriting array, linked list inversion, bubble and optimization, fast discharge, merging, merging two sorted array, the step jump, and the two numbers, the list is determined with a ring, the pieces of data found from 100W minimum ten
21.cpu occupancy rate, the investigation of the use of command?
22. The lock of the upgrade process (no lock - biased locking - Lightweight lock - heavyweight lock, explain each process)
23. The scene out sql question
24.B + tree to explain the principles, drawn.
25. Some say they are familiar with design patterns, application scenarios?
26.http and tcp What difference does it make? tcp and udp What is the difference? tcp three-way handshake, waving four times, drawn.
27. The handwriting singleton. Usually double lock, enumerate way
28 hystrix talk about service degradation, governance, fuse
29 talk about cas
30.JVM tuning parameters
31. The new generation of how garbage collection?
32 phantom reference soft weak references cited strong references? Object o1 = new Object (); Object o2 = o1; this time GC, which will be recycled out?
33. The garbage collection algorithm
34. The garbage collector
35 hand-painted JVM memory structure
36. I have had any knowledge of the use of middleware to do? I think, zookeeper's watch mechanism, why Tomcat class loader garbage collection policies contrary to their parents delegation model, redis's, MQ publish / subscribe model, etc.
Summary: personally think that more than ordinary knowledge of the company generally will not ask so deep, but still need to master, study its principles. Many people say that this year working hard to find, as long as the sink in the heart study and master the knowledge, then, still many opportunities. The interview is now not only let you answer, more is to let you use a pen to write out and explain the problem. So it can not just back down to cope with the interview, then it is basically gone.
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