How to learn JAVA systematically?

A veteran who has been playing Java for many years will take you on board to learn Java comprehensively and systematically, and will also teach you how to learn to get a good offer this year.

When it comes to a comprehensive system, it is based on the knowledge content that most companies currently require for recruitment. After all, we all learn Java for high-paying jobs. "Historical Records" says, "Everyone in the world is for profit." "Come on, the world is all about profit." It is human nature to learn Java technology for a high-paying job, and it is also the goal of most people.

Let’s first take a look at what skills are needed to recruit Java programmers on the market:

Have you looked at the recruitment requirements of the above three companies and found that the current requirements for junior Java engineers are similar? , the main frameworks are SpringMVC, Mybatis, SpringBoot, and SpringCloud. The databases are MySQL and Oracle. Generally, small and medium-sized companies use MySQL, while slightly larger companies mainly use Oracle, as well as basic Web-related content and the use of some tools such as git, Maven, and SVN.

So we must first understand what technologies we need to learn in the current market. The knowledge you learn must be put to use and keep up with the forefront of the times. The so-called comprehensive and systematic learning of Java, we must first understand what we should learn. The comprehensive and systematic Java content is as follows:

1. Basics of JavaSE

JavaSE is a standard version and the basic part of the Java language. Various frameworks derived from Java (such as Spring series) various products are based on the JavaSE standard. JavaSE is the foundation for the upward development of Java. The underlying foundation of any advanced Java product is JavaSE. Generally speaking, this is the "father" of all children. If you don't learn JavaSE well and don't understand it thoroughly, it will be like a bible when you learn the framework later. Therefore, the importance of this part of JavaSE is self-evident. I hope all beginners will keep it in mind.

Mainly includes: data types, basic syntax, operators, process control, arrays, object-oriented, common classes, exception handling, collections, IO streams, multi-threading, reflection, annotations, parsing, network programming .

PS: The content of JavaSE is very large. Any set of JavaSE tutorials will not explain all the methods. They will only select the content commonly used in daily work to explain, so many of the contents in JavaSE are After class, I slowly learned about it in the API documentation. You must learn to take the initiative to learn and cannot just sit back and wait.

Recommended learning book: Java Core Technology

This book was written by an American. Since its publication, it has been favored by the majority of Java programmers. It has been a best-seller and is the most popular Java programmer. Classic books. It covers all the basic knowledge of Java platform standard version JavaSE, provides a large number of complete and practical application examples, and introduces in detail the basic knowledge of Java language, object-oriented programming, interfaces and internal classes, event listener model, and swing graphical user. Interface programming, packaged applications, exception handling, login and debugging, generic programming, collection framework, multi-threading, etc. (This book is a must-read for every Java programmer)

2. Database

Database is a must-learn content for learning Java language. A common database is MySQL and Oracle. As beginners, they usually focus on learning MySQL. Generally, small and medium-sized enterprises will choose MySQL database. Larger Internet companies will choose Oracle. Learning Oracle is more complicated than MySQL. It is recommended The main thing is to learn the MySQL database, and Oracle can be used as an understanding. Learning the database is relatively simple. The basic operations are addition, deletion, modification and query.

3. Web development

Web front-end content: HTML/CSS/JavaScript/ (front-end page)

Note: Java back-end development does not require too much attention Processing of HTML pages and CSS, but at least you must be able to use simple HTML, and JavaScript is a must, because after all, Javaweb back-end programmers have to be exposed to the use of AJAX to process data and display. Of course, if you only focus on server-side implementation without considering any user interface, you don’t need to pay attention to HTML, CSS, and JavaScript. However, although there are many developments that are completely separated from the front-end, it is impossible to not care about the front-end, especially JavaScript, but The front end can completely ignore any implementation of the server backend.

Recommended learning book: "The Art of JavaScript? DOM Programming" (Second Edition)

It makes sense that this book is the most recommended front-end introductory book by everyone. He can truly let everyone understand DOM script programming, or the ideas and principles behind front-end programming technology. For beginners, this book has no threshold. Just follow the book examples and write code step by step. We will know how to operate and control browser elements, and learn how to achieve simple page effects. This simple and easy sense of accomplishment is the most valuable experience when getting started with a programming language.

JavaEE content: Servlet/JSP

Although JSP is rarely used on the Internet now, it may be replaced by some templates or JS?AJAX methods, but I think it should still be Get in touch with it, what to do if you don’t know how to use it, and it is a standard component of Java EE for dynamic web page implementation. Learning the JSP process can also better help us understand the process of web sessions and understand what we need to know about web sessions. If you learn Javaweb and JSP without touching it, it is equivalent to learning to use Springboot without touching SpringFramework at all. Wouldn't it be confusing? Including developing Javaweb? The concepts we must know such as Web application context, request object, response object, HttpSession, Cookie, etc. are all reflected in the contact learning of JSP and Servelt, as well as some relatively rare EJB? JSF? JMS? and? Java? Felix et al.

Some beginners are not clear about these and will inevitably have misunderstandings, especially some more mature engineers. I can only say that they are very ignorant. They are just code machines. In fact, they are confused about application development and design. , just follow what others say.

There is no technology that will never be eliminated, and there is no universal technology that will always be popular. It depends on the environment and occasions in which it is applied. The technology and tools that meet my needs are good and right.

Four. Advanced Framework

1. Springframework?Core IOC container

2.Spring?boot?A Spring tool that more comprehensively improves efficiency based on Spring

3. The most popular ORM frameworks nowadays are Mybatis and MP (Mybatis plug-in). Hibernate is optional to learn.

4. Template technology is relatively mature. Freemarker

5. Spring Cloud microservice framework, a complete set of distributed system solutions provided by Spring Cloud.

5. Tools

Maven? is a tool for building and managing projects. svn? and git are project source code and related document management tools developed through team collaboration, which require learners to initially master its application.

Like Tomcat, jetty?, resin, JBoss, GlassFish?, etc. are all servers deployed to run Java? web applications.

The above is the general content for beginners to learn. I tried my best to speak from the perspective of beginners. I didn’t write it in a particularly complicated way, for fear that beginners would not be able to understand it and it would not be of substantial help. So I try to make it as simple as possible in vernacular and list the main Java knowledge points for everyone to learn.

Now that we know the general content of Java, the following is how to learn Java well in the best way to achieve the level of employment. First, we should understand the current level of finding a job. How it is. If you have any questions about learning Java, about how to improve your learning of Java, learning methods, learning skills, and the technical level to quickly achieve employment, you can ask me at any time. This is the Java learning exchange skirt that I have established for 5 years. The three are 494, the middle three are 801, and the last three are 931. If you have any questions you don’t understand, you can ask them there at any time, and you can also download learning materials for various stages of Java there.

How much Java can I learn before I can get a job: For most students who are new to Java, what they are most concerned about is what I need to learn and how much I need to learn before I can find a relevant Java R&D job. post.

Different software companies have certain differences in the level requirements for R&D personnel. From the perspective of most small and medium-sized enterprises, if they can accept an IT technician joining the company, they usually need to have the following abilities.

1? Understand and master Java’s core object-oriented design ideas and code construction, and be able to design and write business functions in an object-oriented manner;

2? Proficient in the development of at least two databases, Such as Oracle, mySql, and be able to write basic commonly used and advanced SQL statements proficiently;

3. You must master and skillfully apply the Springframework IOC container, have an in-depth understanding and application of IOC and AOP concepts, and use MVC to implement web? The request is processed;

4. Proficient in the ORM framework myBatis and JDBCTemplate for Java processing databases, and should also have an understanding of Hibernate;

5. Proficient in using Spring to enhance the tool collection Spring?boot;

6? At least be proficient in using Eclipse and IDEA integrated development tools to build applications;

7? Be able to basically master the use of MVN?GIT?Maven? in projects;

8? Front-end development must master JavaScript and commonly used JS frameworks

The above are the basic requirements for entry into small and medium-sized software companies. If you can reach this level, find a Java job The job shouldn't be difficult.

Recommended learning method: system video tutorial + book assistance + guided guidance

Video tutorial: For Java beginners, watching videos is also the most common way to learn. Video tutorials will The commonly used knowledge at work is explained, and the videos are generally divided into chapters. Each section only talks about one knowledge point, making learning more clear. However, the video tutorial should be as complete as possible, preferably a complete set of video learning.

Book assistance: Books are convenient for supplementing theoretical knowledge, making it easier to understand Java's object-oriented core design concepts and code practice functions.

PS: But most people don’t have the patience to read the book, so most people only learn by watching video tutorials. If you can watch it, watch it; if you can’t watch it, don’t watch it.

Some people have given guidance: Most people cannot learn Java very well by relying solely on their own abilities, because you don’t understand this industry and don’t know how to learn it. If you want to find a job by learning Java by yourself with zero foundation, , the probability is extremely low. Therefore, it is recommended that if you really want to do this, try to find someone to guide you. If you have any questions you don’t understand, you can ask directly to avoid detours and improve efficiency. The quality of study determines the salary and starting point of future work, so it should still be taken seriously.

The Importance of Projects

Many Java beginners say they "know it" after watching some videos and learning it for a while. Here I need to correct a problem for everyone. I hope that everyone who is learning Java can understand what the core of learning programming is. ?In fact, in my opinion, there has never been such a saying about learning programming. Learning programming is different from mathematics, physics, and chemistry in junior high school. Memorizing some formulas and doing the same type of exercises will prove that you can do similar types of questions.

?Programming only talks about the level and level of technical ability. What can best prove the stage of technical level is the development of Internet products during the project, the quality of the code written, and the debugging ability. Similarly, how is your ability to find bugs, how is your ability to conceive the overall layout of functional modules, etc. ?As a beginner, if you want to reach the entry-level level, you must have the coding ability for some simple projects. The most important thing for a beginner is to cultivate your own programming thinking. Every program is different, and you cannot memorize them all. After all, learning programming does not rely on rote memorization. Only when you can code and write something independently can you have a chance of employment.

So the ability to do projects can measure the stage of a person's learning level, and often those who say "know it" often haven't written much code, and they can't complete a project. , this is just talking on paper, completely misunderstanding what you are learning about programming, and you don’t know where you should go.

So in the overall process of learning, a Java beginner must have two projects that can be used and can be written on the resume as capital to find a job, and he must be familiar with these two projects. Only by having a good understanding of everything in Java can you succeed in the final interview. If a beginner, after learning all the content of Java, is still not able to do simple projects, then his entire learning process will be in vain and he will not achieve the ultimate learning goal. It’s just that the quality of learning is not up to par. Therefore, I hope everyone can understand the importance of the project, because there are too many Java beginners who do not know what the final purpose of learning is, and end up wasting time in vain.

Learning mentality:

Learning programming is definitely not a simple matter. In other words, it is still quite difficult. After all, if you can go out and find a job, it will cost you as little as five or six thousand, or as much as Thousands of jobs. None of this knowledge can be learned casually by anyone. Regarding this learning mentality, I hope to remind everyone to focus on "learning", because I found that many Java beginners study as if they were "completing the task". The so-called completing the task means "I watched these videos "Can I find a job after I finish learning all this?" "Can I find a job after I finish learning all this?" Completing the studies does not mean "learning". These are two different concepts.

Do you understand it?

Can you apply it?

Are you paying attention?

You yourself should know best. I found that those who treat learning as completing a task, none of these people are patient, and they deceive themselves in their hearts: "After watching these videos, I You can find a job." In the end, I gradually realized that I was completely deceiving myself, and finally gave up and said that I was not suitable for this study. In fact, there is only one truth behind the mask of these people: they have no patience to learn and do not like to learn. This is caused by previous experiences and years of habits.

So the correct learning attitude must be to focus on the learning itself. You have to learn these knowledge, these contents, and these techniques, which need to be gradually accumulated day by day, not in a short time. Time can achieve results.

PS: If you have no patience or interest in learning, I advise you not to learn programming. Learning programming is definitely a patient job, and it is also an industry that requires continuous learning and recharging. In other words, we have reached the information age. People who don’t like learning and have the patience to learn knowledge cannot survive in the information age. This is true for any industry. People who don’t learn, don’t make progress, and don’t keep up with the times will definitely will be eliminated.

In the end, people who can find jobs by self-taught Java basically have the following points:

1. Have strong learning patience and enterprising spirit

2. Not lazy , write enough codes, practice makes perfect

3. Have certain learning ability, be good at self-study and solve problems by yourself

4. Can write some simple projects independently

< p>The above contents are all handwritten by me. From the perspective of Java beginners, I hope to use easy-to-understand language to let everyone clearly understand the learning content of learning Java comprehensive system, and what level should be achieved. I got a Java job offer, I hope it can be helpful to everyone.