What to write after learning the basics of Java?

Question

Java

I learned the basics of Java (OOP, loops, arrays, variables, etc.), but I want to reinforce my knowledge. Please advise what to write that would cover all these topics.

Answer 1

Write a program

Answer 2

acm.timus.ru/problemset.aspx
https://projecteuler.net/archives

Answer 3

If you literally answer your question, then any accounting system, for example, a telephone directory. Store data in a file (or not store at all).
If you want advice, then:
Learn java core by studying from 8 to 17:00 - this is a month maximum. If you want to become a professional (that is, get paid for writing programs in java) and you are young, then read a little about interview questions and get a job as a junior. If you are over 30 then:
1. java - this is knowledge of English at the level of reading without a dictionary - required. I write and communicate verbally in English highly desirable. If you don't know, learn.
2. java is a server software for accounting systems. For example, a program in a bank. Until you can start thinking about how to write an application that will never crash, and if it does, then it will be immediately clear from the logs what is wrong - the path to further study is closed to you. That is, in a regular telephone directory, when adding an entry to the database, you can provide everything. Starting from the fact that the base fell, ending with the fact that they planted 100 people and enter incorrect values ​​for you for days.
PS
well, not at all on the topic, but you probably know. Java core narrow knowledge is essentially not needed by anyone. We need frameworks, for example, hibernate and dozens of them.