Self-study java, to what extent can I start looking for a job?

I understand friends who have just started learning Java, especially those who have no money and no background. The question they care about is: How much can Java learn before they can find their first job? Everyone is realistic and has the same goal, all in order to get a well-paid job like others. So how much Java knowledge does a Java beginner have to learn to find his first Java job?

In fact, junior Java development posts do not have high requirements for practitioners. Usually, if you can skillfully use the common spring mvc, you can find your first job (probably outsourcing). But laymen are inevitably uneasy and have no ideas. How far can Java learn to get a job? From the perspective of how a programmer was born, this paper expounds what interviewers will ask and what job seekers should prepare.

1, Java core aspects, collection, multithreading, exception handling, IO, object-oriented, generics, comments, reflection ... all kinds of programming general grammars may be asked, such as asking the difference between ArrayList and LinkedList; Using Java to realize data structures such as stack, linked list, queue, hash table and tree. Practice various sorting algorithms.

2. As for the front-end foundation, HTML5 CSS3 JS (as complicated as Java, it can be used), don't think that you are a back-end engineer and you won't be a front-end one. In practical work, the layout of div+css must be sloppy, and the dom operation of JS must be powerful.

3.web server: Tomcat and Nginx server structure, configuration file, Servlet, JSP, filter, listener, http protocol, etc. Tomcat directory structure must be well known. You can always deploy the webapp manually. Know a little about where the virtual host is configured, where the port number is changed, and the contents in the web-info folder cannot be accessed externally.

4. In terms of database, you can simply add, delete, modify and query, and have some basic concepts, such as how to handle transactions and how to batch process in JDBC. I can write SQL statements to add, delete and change queries, understand concepts such as stored procedures, and optimize query conditions through indexes. Multi-table association, left outside and right outside can not be timid. Please note that at least one commercial database must be used, and Mysql is recommended.

5. In terms of Web framework, you need to know the basic syntax of SSM or Spring Boot or Chunyun from front to back in the form of full stack. At least with the short-term help of the project manager, you can write code according to other people's examples. As long as fresh graduates can clearly explain the grammatical points and processes of relevant frameworks, they can at most explain the usage of components such as mybatis. As for redis and dubbo, there is no requirement at all. You need to have the practical operation ability of Spring+Spring MVC+mybatis framework (not the development ability of commercial projects). As for Spring Boot or Chunyun, so much the better. Understanding the ORM process of Spring in IOC, AOP and Mybatis is the core of WEB framework inspection.

6. In terms of comprehensive skills, I can know the basic knowledge of data structure (the skills of sorting linear tables and some trees), the basic knowledge of operating system (generally limited to the concept of thread process) and the basic knowledge of network communication (generally limited to the network communication model and tcp udp protocol), but this is just a "need to know".