There are guides out there for installing Apache Netbeans. There are guides out there for installing OpenJDK.

There are NOT any guides out there that closes the loop, at least not to my knowledge. Now that Oracle has changed their licensing agreements, many companies accustomed to getting the JDK for free are turning to OpenJDK.

Let this help those trying to make the transition or just getting started.

Go to the Apache Netbeans download page.

https://netbeans.apache.org/download/

Click the download button for the latest LTS version.

Always use the latest LTS version of the IDE; it is the least likely to have bugs. Long-term support (LTS) releases benefit from their NetCAT community testing process, and remains available and supported for a year. Other releases have access to new features but are not thoroughly tested.

Find the “Deployment Platforms” section to determine which JDK is required to run the IDE.

Now, install OpenJDK BEFORE installing Netbeans.

Go to the OpenJDK download page.

https://jdk.java.net/

Download the JDK version necessary to run the IDE.

For example: JDK 14.

Extract the downloaded zip file.

Extract to C:\Program Files\Java.

Add the java JDK binary to the PATH environment variable.

Execute command in Admin Command Prompt.
setx path "%path%;C:\Program Files\Java\jdk-14.0.2\bin"

Close and reopen Admin Command Prompt to reload Environment Variables.

Verify by executing command in Admin Command Prompt. Version displayed should match version you just extracted.
java -version

Set the JAVA_HOME environment variable to point to JDK directory.

Execute command in Admin Command Prompt.
setx JAVA_HOME -m "C:\Program Files\Java\jdk-14.0.2"

Close and reopen Admin Command Prompt to reload Environment Variables.

Verify by executing command in Admin Command Prompt. Output should match path to JDK directory.
echo %JAVA_HOME%

Download Apache Netbeans LTS.

Download the appropiate installer .exe file from the mirror site they recommend.

Launch the installer and follow the installation wizard, using all of the default settings.

You should not encounter any warnings.

Finally, keep enjoying that free JDK!