What the Java interview needs to know clearly

Project Related:

1. What does the project do?

2, clear the value of the project. (Why does this project, it solves the user what pain point, it brings what value?) ）

3, clear the function of the project. (What features are involved in this project?) ）

4, clear the project technology. (What technologies are used in this project?) ）

5. Define the position and role of the individual in the project. (Do you assume a role in this project?) ）

6, clear the overall structure of the project.

7, clear the advantages and disadvantages of the project, if re-design how you will design.

8, clear the highlights of the project. (What's the highlight of this project?) ）

9, clear technology growth. (What technologies have you grown through this project?) ）

Java Basics

1. The difference between List and Set

2, HashSet is how to ensure that the non-repetition

3, HashMap is thread-safe, why is not thread-safe (best drawing to explain the multi-threaded environment is not secure)?

4, HashMap of the expansion process

5, the difference between HashMap 1.7 and 1.8, explain 1.8 what optimization, how to optimize?

6. Final finally Finalize

7. Strong references, soft references, weak references, virtual references

8. Java Reflection

9, Arrays.sort realization principle and Collection realization principle

10, the application of Linkedhashmap

11, Cloneable Interface Implementation principle

12. Exception classification and processing mechanism

13. The difference between wait and sleep

14. How arrays are allocated in memory

Java concurrency

1, the realization principle of synchronized and lock optimization?

2, the principle of the volatile implementation?

3, the Java signal?

4, synchronized the difference between static method and ordinary method?

5. How do I implement all the threads waiting for an event to happen?

6, CAS? What is the defect of CAS and how to solve it?

7. What is the difference between synchronized and lock?

8, Hashtable is how to lock?

9, HashMap concurrency problem?

10, Concurrenhashmap Introduction? Why do you use red and black trees in 1.8?

11, AQS

12, how to detect deadlocks? How to prevent deadlocks?

13. Java memory model?

14, how to ensure that the results of multi-threaded i is correct?

15, the type of thread pool, the difference and use scene?

16. Analyze the implementation principle of thread pool and the scheduling process of threads.

17, how to tune the thread pool, the maximum number of how to confirm?

18, threadlocal principle, when using the need to pay attention to what?

19, the use of Countdownlatch and Cyclicbarrier, and the differences between them?

20. Locksupport Tools

21. Condition interface and its realization principle

22. Understanding of the Fork/join framework

23, the principle of segmented lock, the thinking of reducing the lock force

24, eight types of blocking queues and the characteristics of each blocking queue

Spring

1, beanfactory and Factorybean?

2, the Spring IOC understanding, its initialization process?

3, Beanfactory and ApplicationContext?

4. How is the life cycle of Spring Bean managed?

5. What is the loading process of Spring Bean?

6. If you want to implement spring AOP, how can I implement it?

7. What issues will you notice if you want to implement the spring IOC?

8. How does Spring manage the transaction and the transaction management mechanism?

9. What are the different activities of Spring?

10. What are the design patterns used in Spring?

11. How does Spring MVC work?

12. What is the principle of Spring loop injection?

13, Spring AOP Understanding, each terminology, how do they work with each other?

14, Spring How to ensure the security Controller concurrency?

Netty

1. BIO, NiO and AIO

2, Netty of the major components

3. Netty Threading Model

4, the reason and solution of TCP sticky packet/unpacking

5. What kinds of serialization protocols do you know? Including usage scenarios and how to choose

6, the Netty 0 copy implementation

7, Netty of high performance in which aspects

Distributed correlation

1. Principle and mechanism of bottom-up realization of Dubbo

2, describe a service from the release to the detailed process of being consumed

3, distributed system How to do service governance

4, the concept of the power of the interface

5. How message middleware solves the problem of message loss

6, Dubbo Service request failed how to deal with

7, the re-connect mechanism will not cause errors

8. Understanding of distributed transactions

9, how to achieve load balancing, what algorithms can be implemented?

10. What is the principle of election for the purpose of zookeeper?

11, vertical splitting of the data split horizontally.

12. Zookeeper Principle and Application scenario

13. Zookeeper Watch mechanism

14, REDIS/ZK node downtime how to deal with

15. How to achieve unique serial number under distributed cluster

16, how to do a distributed lock

17, used what MQ, how to use, and other MQ compare what are the pros and cons, MQ connection is thread-safe?

18. How to ensure the data of MQ system is not lost

19. List the database Sub-table strategy you can think of, how to solve the problem of full table query after the Sub-library table

20. Zookeeper election strategy

21. Global ID

Database

1. What is the optimization of MySQL paging?

2, pessimistic lock, optimistic lock

3. Combined index, left-most principle

4. mysql table lock, row lock

5. mysql Performance optimization

6, MySQL Index classification: B, Hash; What is the index of the situation?

7. Characteristics and isolation levels of transactions

Cache

1. What data data is used by Redis, and how does the Redis bottom-level implement

2. Redis cache penetration, Cache avalanche

3. How to use Redis to implement distributed locks

4, how to solve the problem of the concurrent competition of Redis

5, Redis persistence of several ways, advantages and disadvantages of what, how to achieve

6. Redis Cache Invalidation Policy

7, Redis cluster, high availability, principle

8. Redis Cache Shard

9. Redis's Data elimination strategy

Jvm

1. Detailed JVM memory model

2. Tell me what happens next memory overflow, memory leak?

3, talk about Java thread stack

4. What are the judging conditions for the promotion process from the young generation of the JVM to the aging generation?

5, the JVM appears fullgc very frequently, how to troubleshoot the problem on the line?

6. Why does the class load use parental delegation mode, and is there any scenario that breaks this pattern?

7. Instantiation Order of Classes

8, JVM garbage collection mechanism, when to trigger MINORGC and other operations

9. What is a complete GC process (from YGC to FGC) in the JVM

10, various recycling device, their advantages and disadvantages, key CMS, G1

11. Various recovery algorithms

12, oom error, stackoverflow error, PermGen space error

What the Java interview needs to know clearly