java_courses

An overview, sorted by topics, of the projects and learning tasks that I have worked on, or am still working on, towards learning the fundamentions of Java. These were mainly written during courses at JetBrains Adademy Hyperskill. Among them, however, is also code that I wrote in the course of tutorials from other sources, such as YouTube, Reddit or other platforms.

Prerequisites to run my Java programs

At this point I assume you already have installed the JDK (Java Development Kit), as well as the JRE (Java Runtime Environment). In case there is one of them missing, you can get both here:

• JDK: https://www.oracle.com/java/technologies/downloads/
• JRE: https://java.com/en/download/

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1# Compiling a JAVA file:

• Download all Java files related to the program you are intending to run in a new folder on your desktop.
  
  
• Open Windows start menu, type CMD and run it.
  
  
• The standard directory you are currently in is usually
  C:\Users\YOUR_USERNAME (on Win10 at least).
  
  
• Navigate to the folder you created previously, type
  cd Desktop\FOLDER_NAME into the CMD and hit enter.
  
  
• In order to compile your project to bytecode,
  type javac FILENAME.java and, again, hit enter.
  
  
• Now you have the FILENAME.class in your folder at the desktop.
  You can check this by typing dir into CMD, followed by enter.
  This lists all files inside that folder.

2# Running a CLASS file:

• For the program to be executed, you need to run the file containing the main method. To do so, you either open each .java file by making a right-click on the file, choose Open with..., select Notepad. Now look in the first couple of code for a line called public static void main(String[] args) {.
  
  
• Too complicated? I've got your back!
  Alternatively, you may just run one file after another until you found the correct file ;)
  
  
• Since you should still be in your folder on the desktop (see step 1#), just enter java FILENAME and hit enter.

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TROUBLE SHOOTING:

Unable to run javac or PATH entry / Environment Variable is missing. To fix this, open Windows start menu and type environ, this should be enough to bring up Edit the system environment variables - run it.

• Go to the Advanced tab (top side) and click Environment Variables…
  
  
• In the lower part of the upcoming window, you find the System variables, look for the entry named Path (take care, there is another entry with a similar name), highlight / single click it and click Edit…
  
  
• There should be a variable called C:\Program Files\Java or similar. Mine contained something with Oracle in it. Select it and click Browse…
  
  
• Now, navigate to C:\Program Files\Java\ - select the Bin folder - hit 4 times OK, once in each window.
  
  
• In case your CMD is open, close and re-open it. You now can run javac.