Are two classes necessarily equal? Equals? On the contrary?

2. Introduce the collection framework?

What are the differences between the underlying implementation of HashMap Hastable? What about hashTable and ConCurrenthashTable?

4. What is the difference between HashMap and Treemap? What are the low-level data structures?

5. What are the parameters of the thread pool? How is this implemented at the bottom?

6. What’s the difference between sychnized and Lock? Sychnize What case is an object lock? When is a global lock and why?

What is ThreadLocal and how is it implemented? Why don’t you write an example?

8. How does Volitile work?

9. Does CAS know how to achieve it?

Write a singleton pattern in at least four different ways

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2. I have been in the company for a long time and have been comfortable, but I hit a wall in the interview when I changed my job. Need to study in a short period of time, job-hopping can be added.

3. If you have no working experience, but have a solid foundation, and have a good command of Java working mechanism, common design ideas and common Java development framework, you can add.

4, feel very good B, general needs can be done. But the knowledge points learned are not systematic, it is difficult to continue to break through in the field of technology can be added.

5. Ali Java senior bull live explain knowledge points, share knowledge, sorting out and summarizing years of work experience, with everyone to establish their own technical system and technical knowledge in a comprehensive and scientific way!

JVM

1, Please introduce the JVM memory model? Why don’t you tell me what garbage collector you’ve used

2. How to deal with frequent online full GC? What can I do if the CPU usage is too high?

How to locate the problem? How to solve say solution train of thought and processing method

3. Know bytecode? What are the bytecodes? Integer x =5,int y =5.

What class loaders are there, and what files are loaded by them?

Write the class loading Demo by hand

5. Know OSGi? How did he achieve it??

6. What JVM optimizations have you made? What method is used to achieve what effect??

7, classforName(” java.lang.string “) and String classgetClassLoader() LoadClass(” java.lang.string “).

Spring

1, What are the mechanisms of Spring ah AOP underlying how to implement IOC?

2. Does cgLib know? How does it differ from JDK dynamic proxies? Write a JDK dynamic proxy?

The database

1. What are the principles of using mysQ1 index? ? What data structures are indexed? What is the difference between 3+tree and B tree?

2. What storage engine does mysQ1 have? What’s the difference? To detail!

3, how to design the database level of high concurrency system? What are the types of database locks? How do you do that?

What are database transactions?

Depots table

1. How to design a scheme of database and table division that can be dynamically expanded and reduced?

2. Which sub-database and sub-table middleware have you used? What are the advantages and disadvantages? What do you know about the underlying realization principle of sub-table middleware?

3, I now have a sub-database sub-table system, the future system needs sub-database sub-table, how to design, so that the sub-database sub-table system dynamic switch to the sub-database sub-table system?? TCC? That if appear network reason, network connect impassability how to do??

4. Distributed transactions? How did you solve it?

5, why should be divided into the database and table??

6. Do distributed addressing algorithms know consistent hash? Write the Java implementation code by hand? If the userId retrieves a fragment, what if I want to check the data over a continuous period of time?

7. How to solve the problem of primary key of sub-table?

Distributed cache

Why single-threaded Redis is more efficient than multi-threaded memched?

2, What data types are redis used in what scenarios?

3, How to implement the primary/secondary replication of REids?

4. How to design distributed locks with Redis? Is zK ok? How to achieve ah, which of these two is more efficient?

5. What are the disadvantages of redis persistence? ? What about the underlying implementation?

6, Redis expiration policy have what LRU write Java version of the code?

Distributed Service Framework

1, the implementation process of dubbo said that the registry is down can continue communication?

2, zK principle know what ZK can do Paxos algorithm know? Talk about the principle and implementation?

What serialization protocols does Dubbo support? Hessian’s data structure, PB, is the most efficient.

NIO,BIO,AIO, NIO, NIO, AIO, NIO, AIO, NIO, AIO

5. What are the dubbo replication balancing and high availability policies?

6. What is the difference between dubbo and thrift?

Distributed message queue

What are the advantages and disadvantages of message queues?

2, how to ensure that the message queue is highly available how to ensure that the message is not repeated consumption

What are the advantages and disadvantages of Kafka, ActivemQ, RabbitMQ, RocketMQ?

4. If you were to write a message queue, how would you architecture it? Tell me what you think

Distributed search engine

1. How is the working process of ES realized? How to implement distributed ah

2, ES in the case of a large amount of data (billions of levels) how to improve query efficiency ah?

3. What is the working process of ES query? Lucence at the bottom, inverted index, okay? What is the difference between ES and mongdb?

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High concurrency and high availability architecture design

1. How to design a high concurrency high availability system

2. How to limit the current? How is it done in the project

3. What are the consequences of improper use of cache?

4, how to fuse ah? What are the fuse frames? Do you know the specific implementation principle?

5, how to degrade how to split the system, how to split the database????

Communication protocol

TCP ‘IP layer 4

2. HTTP workflow? ? What are the differences between http1.0 and http1.1?

3, TCP three handshake, four layer break up workflow draw a flow chart why not four five times or two ah?

4. Draw the HTTPS workflow. How to achieve it? How to prevent being caught bag?

algorithm

1, relatively simple, I have a file, 4.5 billion Arabic numerals, how to repeat ah how to find the largest number ah?

The data structure

1. Binary tree and red-black tree, etc.

Source code used in the classical design ideas and common design patterns