How do I practice Java in IntelliJ IDEA?
<p>Using a Mac.</p>

<p>I am trying to get used to Java so I am following this tutorial <a href="https://programmingbydoing.com/a/an-important-message.html" rel="nofollow">https://programmingbydoing.com/a/an-important-message.html</a></p>

<p>So I made a .java file and opened it in IntelliJ IDEA but somehow I can't get it to run. I did Build and then Run and for some reason there isn't anything I can click to actually run the program. I can only run it from the Terminal if I do <code>java FirstProg</code>.</p>

<p>Also I can't seem to get IntelliJ to open these .java files automatically. Any time I click a .java file it opens in XCode. I tried right clicking the .java file and Open With to tell it to always open in IntelliJ but it doesn't seem to stick, and even then it doesn't seem to open the file, it goes to the main IntelliJ menu (Open Project, etc).</p>

<p>Setting up software like this is always a huge weakness for me because I can never get it right. I don't know what I'm doing wrong.</p>