Update Running_Code.mdx

content/1_Intro/Running_Code.mdx

@@ -1,7 +1,7 @@
 ---
 id: running-code
 title: Running Code
-author: Benjamin Qi, Hankai Zhang, Anthony Wang, Nathan Wang
+author: Benjamin Qi, Hankai Zhang, Anthony Wang, Nathan Wang, Nathan Chen
 description: Options for running your language of choice.
 prerequisites:
  - choosing-lang
@@ -42,7 +42,7 @@ You can also share code with [pastebin](https://pastebin.com/) or [hastebin](htt
 
 <CPPSection>
 
-You can run from the command line and use a text editor of your choice.
+You can run your C++ programs from the command line and use a text editor of your choice. Read below for different options to create and run C++ programs.
 
 ## Text Editors
 
@@ -269,6 +269,57 @@ Now you can easily compile and run `name.cpp` from the command line with `co nam
 
 </CPPSection>
 
+<JavaSection>
+
+First, download the [JDK](https://docs.oracle.com/en/java/javase/14/install/overview-jdk-installation.html#GUID-8677A77F-231A-40F7-98B9-1FD0B48C346A). Then, test that you can use the right commands.
+ 
+On Windows, open `cmd` and type the following command into the prompt: 
+
+```
+java
+```
+
+If you get the below result, you may have to add the JDK to your [PATH](https://docs.oracle.com/en/java/javase/14/install/installation-jdk-microsoft-windows-platforms.html#GUID-A7E27B90-A28D-4237-9383-A58B416071CA) variable.
+
+```
+'java' is not recognized as an internal or external comman,
+operable program or batch file
+```
+
+If you get a list of command arguments to the `java` command, then you're probably good to go.
+
+<IncompleteSection>
+
+What do you have to do on Mac to get Java working the command line?
+
+</IncompleteSection>
+
+Running a Java file off of the command-line is relatively simple after the JDK is downloaded. 
+
+Consider this code of `Main.java` and assume it is in a file on your computer:
+
+```java
+public class Main {
+ public static void main(String[] args) {
+  System.out.println("Hello World!");
+ }
+}
+```
+
+Use the `cd` command to get to the directory that contains `Main.java`. Then, run the following command to compile the code:
+```
+javac Main.java
+```
+If it runs successfully, a file called `Main.class` will show up in the same directory, which can be executed with the next command:
+```
+java Main
+```
+If everything goes accordingly, the console should output `Hello World!`.
+
+If you do USACO-style file I/O, meaning that files are in the "local directory", then the files must be located in the same directory as the source code (if you use the above method).
+
+</JavaSection>
+
 <PySection>
 
 Download Python through [the official website](https://python.org). On Windows and Mac, you can download executable files directly; on Linux, you must either download the Python source code and compile from source, or obtain Python through your package manager.