Design Patterns VS tutorials

After that, more practice, and then Design Patterns (as in the famous book of the "Gang of Four": "Design Patterns: Elements of Reusable Object Oriented Software"). Here I'd recommend "Head First: Design Patterns" and Java Design Patterns as well as Refactoring Guru (the sites are more reference than course).

For Design Patterns - any resource recommendation that misses Java Design Patterns and Refactoring Guru (also for Refactoring) as well as *Head First: Design Patterns, has failed.

A massive list of design patterns and how they could be implemented (in Java) can be found here.

https://java-design-patterns.com/ has example code for things like object pools that can help with memory management.

Sidenote: I would not really use the GoF Design Patterns book anymore. Too dry. I would use "Head First: Design Patterns" - much more modern, much easier to read, or Refactoring Guru or Java Design Patterns (uses Java, but again, only for illustrations).

Also: https://java-design-patterns.com and https://refactoring.guru/design-patterns

Use either Java Design Patterns or Refactoring Guru. Both resources are far higher quality than yours.

Java Design Patterns

Java Design Patterns - IMO one of the most accessible sites with very easy explanations

A hint: go to Java Design Patterns and go through the patterns to figure what could fit.

But ok, lets try with this example, line 40 : https://github.com/eugenp/tutorials/blob/master/testing-modules/junit5-annotations/src/test/java/com/baeldung/junit5/nested/OnlinePublicationUnitTest.java This code tests a function which is 5 lines long, called only once. It doesn't even deserve a method declaration, this is complexity for the sake of testability. 6 months from now, when you look for articles filtered by user membership, you are not going to find this function. You will be lost in a maze of method declarations. Fragmenting your execution flow is a bad idea, especially for testability purposes. The test code is even more complex than the code being tested.

Baeldung has a lots of tutorials... GitHub - WebModules

You can checkout more examples on below GitHub Repository. https://github.com/eugenp/tutorials/tree/master/json-modules/json-2

I found an example for you online: https://github.com/eugenp/tutorials/tree/master/docker/docker-spring-boot-postgres

git clone https://github.com/eugenp/tutorials.git

The best way is to find a job, write horrible code, get absolutely humiliated on the MR and then you will start getting all that stuff. A second option would be to read code from others, I always keep this repo open https://github.com/eugenp/tutorials.