Please ensure that: Your code is properly formatted as code block - see the sidebar (About on mobile) for instructions You include any and all error messages in full You ask clear questions You demonstrate effort in solving your question/problem - plain posting your assignments is forbidden (and such posts will be removed) as is asking for or giving solutions. Trying to solve problems on your own is a very important skill. Also, see Learn to help yourself in the sidebar If any of the above points is not met, your post can and will be removed without further warning. Code is to be formatted as code block (old reddit: empty line before the code, each code line indented by 4 spaces, new reddit: https://imgur.com/a/fgoFFis ) or linked via an external code hoster, like pastebin.com, github gist, github, bitbucket, gitlab, etc. Please, do not use triple backticks (```) as they will only render properly on new reddit, not on old reddit. Code blocks look like this: public class HelloWorld { public static void main(String[] args) { System.out.println("Hello World!"); } } You do not need to repost unless your post has been removed by a moderator. Just use the edit function of reddit to make sure your post complies with the above. If your post has remained in violation of these rules for a prolonged period of time (at least an hour), a moderator may remove it at their discretion. In this case, they will comment with an explanation on why it has been removed, and you will be required to resubmit the entire post following the proper procedures. To potential helpers Please, do not help if any of the above points are not met, rather report the post. We are trying to improve the quality of posts here. In helping people who can't be bothered to comply with the above points, you are doing the community a disservice. I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns. More on reddit.com

In image 3 you have multiple paths still pointing to JDK 11... windows is picking the first java.exe it comes across (which is in the JDK11 folders) You need to remove the Eclipse Adoptium and Microsoft\jdk-11.0.12.7-hotspot environment variables Ensure the same thing hasn't happened in the user specific PATH variable - you only showed us the system PATH variable ALSO (important) remove the Common Files\Oracle\Java\javapath environment variable. Oracle does some crappy workaround to try and point you to the "latest" of their JDKs by installing shortcuts in that folder - get rid of it, you don't need those as it only adds to the confusion and causes issues similar to the above. Restart after this and try again - if it's still not working then post updated screenshots Basically you should ONLY be pointing to 1 folder with java.exe if you want "java -version" to run that specific version on the command line You can also technically run: C:\Program Files\Java\jdk-20\bin\java.exe -version and this will output the desired version number. But if you want to be able to run just "java -version" then you have to do the above steps. As others have noted Java isn't really "installed" - it's just about telling programs where the exe is. Most IDEs like IntelliJ will let you specify the path without relying on the environment variables or they may also come with a built-in Java version, it really depends on how you want things to be configured. More on reddit.com

Reinstall JAVA, it should register the .jar extension and it hasn't. More on reddit.com

First things first, when you "install" Java, that simply means the JDK is put into some folder, usually in C:\Program Files\Java, and the value of your PATH environment variable is updated to include the path to the java.exe. If you just download and extract a ZIP file to wherever, which is what I suspect you're doing, Windows isn't going to automatically going to know what to do with this thing you've downloaded. You need to download a proper installer, which will be a file that ends in either .exe or .msi. Secondly, what do you mean by the "official website"? There are several different vendors of the JDK, including Oracle, the Eclipse Foundation, IBM, and Amazon. Which website are you downloading from? I recommend using JDK 17 from Adoptium: https://adoptium.net/temurin/ . Click on "Latest LTS release" and you should be good to go. More on reddit.com