Hello LVM,

        Thanks for asking this question. We will be pleased to answer you. To learn and master Java, and become  Java Full Stack Developer you just need to follow the following steps:-

• First, you need to learn Backend Technologies, for that -

1. Java, multithreading, collections, JDBC, etc.
2. Spring framework
3. Hibernate
4. Get a good hold of SQL. You can use MySQL.
5. Learn how to deploy web servers Apache, database servers and configure them.
6. Learn to use Nix based open source systems (ubuntu, centos). User management, firewall management, ssh, etc.

• Learn Frontend technologies:-

1. Start learning Html, CSS, JavaScript
2. Try to understand how browsers generally work and to debug front-end in web browsers.
3. Learn about responsive UI and a UI framework like bootstrap.
4. Learn JavaScript MVC framework like Angularjs.

• You need to have a clear concept, especially on HTML/ CSS, JAVASCRIPT.
  
• Be sure about the fundamentals of web development.
• Test your knowledge, apply the courses you learned.
• Knowledge of programming concepts can help to improve coding skills. Some theories/knowledge to acquire before pushing ahead are:
1. Servers and their functioning
2. Networks and their nuances
3. Web-hosting environments
4. Algorithms and their formulation
5. Data structures (types, properties, and use)
6. Programming technologies
7. Databases and their management
• Become familiar with all the technologies, but master one at least.
• Even you have been prepared best, you should still learn relevant technologies for your personal improvement.
• You can take Online/ Virtual Courses offered by The Odin Project, Treehouse, Codeacademy. 
• The most important part is getting Practical Exposure. For that, you need to know- the right way to structure code, data structure, the location of computational work, means to separate files, environment to host big data files. 
• Join projects on technologies outside your expertise. Companies will appreciate these initiatives. 
• In the beginning, the journey may look hard, but the experience makes it easier. 

For more feel free to ask us ....