The most comprehensive in history, someone finally sorted out the knowledge points that Java programmers must learn in interviews, which is very inspiring

JVM

Regardless of the level of Java practitioners, JVM is a hurdle that must be overcome when advancing. Whether it is a job or an interview, JVM is a required test. If you don’t understand JVM, the salary will be very bad (nearly 70% of the interviewers hang on JVM)

Introduced in detail JVM about threads, memory model, JVM runtime memory, garbage collection and algorithms, four reference types in Java, GC generational collection algorithm VS partition collection algorithm, GC garbage collector , JAVA IO/NIO, JVM class Major knowledge points of loading mechanism.

basic concepts:

JVM is a hypothetical computer that can run Java code, including a bytecode instruction set, a set of registers, a stack, a garbage collection, a heap and a storage method domain. JVM runs on the operating system, it has no direct interaction with the hardware.

 

There are too many detailed knowledge points, and the copy is too long, see "Java Core Knowledge System"

JVM directory

Java collection

Usually, our program needs to know how many objects to create according to the program running time. But if it is not for the program to run, at the stage of program development, we simply don't know how many objects are needed, or even its exact type. In order to meet these conventional programming needs, we require that any number of objects can be created at any time and anywhere, and what should be used to accommodate these objects? We first thought of arrays, but arrays can only hold uniform types of data, and their length is fixed, so what should we do? The collection came into being!

• 1. Interface inheritance and implementation
• 2、List
• 3、Set
• 4、Map

Java collection framework diagram

There are too many detailed knowledge points, and the copy is too long. See "Java Core Knowledge System" in which there is a detailed decomposition version of the collection diagram to correspond to each knowledge point (see table of contents)

 

Java multithreaded concurrency

Let's take a look at the concurrent knowledge base system diagram:

 

1. How to implement/create Java threads?
2. 4 kinds of thread pools?
3. Thread life cycle (state)
4. 4 ways to terminate threads
5. What is the difference between sleep and wait?
6. The difference between start and run?
7. Java background thread
8. Java lock
9. Basic thread method
10. Thread context switch
11. Synchronization and deadlock
12. Principle of Thread Pool
13. Java blocking queue principle
14. Usage of CyclicBarrier, CountDownLatch, Semaphore
15. The role of the volatile keyword (variable visibility, prohibit reordering)
16. How to share data between two threads?
17. ThreadLocal function (thread local storage)
18. The difference between synchronized and ReentrantLock
19. ConcurrentHashMap concurrency
20. Thread scheduling used in Java
21. Process scheduling algorithm
22. The concept and characteristics of threads

There are too many detailed knowledge points, and the copy is too long. See "Java Core Knowledge System" in which there is a detailed decomposition version of the collection diagram to correspond to each knowledge point (see table of contents)

 

Deep analysis of spring principle

Spring is adopted by more and more microservice practitioners due to its many advantages. If you are proficient in Spring, you can become a leader in the field of rapid application development. However, you must know why. This article will help you understand the operating mechanism behind Spring from the perspective of Spring source code and core implementation principles.

Introduction catalog

1. Features of Spring
2. Spring's core components
3. Spring commonly used modules
4. Spring main package
5. Spring common annotations
6. Spring IOC principle
7. Spring APO principle
8. Spring MVC principle
9. Spring Boot principle
10. JPA principle
11. Mybatis cache
12. Tomcat architecture

 

There are too many detailed knowledge points, and the copy is too long. See "Java Core Knowledge System" in which there is a detailed decomposition version of the collection diagram to correspond to each knowledge point (see table of contents)

Forward this article I focus on private letter reply [ schema information ] advice on how to get the "core knowledge" approach

spring principle

Microservice

Microservice is a knowledge point that you have to master in the Internet industry today, and it is also the most popular and popular knowledge. Let's take a look!

1. Service registration discovery
2. API gateway
3. Configuration Center
4. Service tracking
5. Service fusing
6. API management

 

There are too many detailed knowledge points, and the copy is too long. See "Java Core Knowledge System" in which there is a detailed decomposition version of the collection diagram to correspond to each knowledge point (see table of contents)

Forward this article I focus on private letter reply [ schema information ] advice on how to get the "core knowledge" approach

 

Because the copy is too long, I won’t introduce them here. The core knowledge summary knowledge points also include Netty and RPC, network, log, Zookeeper, Kafka, RabbitMQ, Hbase, MongoDB, Cassandra, 24 design patterns , Load balancing, database, consistency algorithm, Java algorithm, data structure, distributed cache and so on.

 

This knowledge system is suitable for all Java programmers to learn. There are detailed explanations and introductions on the knowledge points in the above catalog. Mastering all the content of this knowledge point will give you a qualitative improvement. It also summarizes many interview processes. A summary of the questions encountered and the corresponding answers.

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