I downloaded the Oracle SQLDeveloper, but when I opened it, it said that it requires a minimum of Java 8 and gave me the website for the download. I went on and downloaded Java
Previously, only JDK 8 worked with Oracle SQL Developer.
But, per https://www.oracle.com/tools/downloads/sqldev-v192-downloads.html, JDK 8 or 11 are required. (there is some misleading documentation that says JDK 8 or higher, but it must be 8 or 11). Also, per Oracle, JDK 11.0.7 is certified for Mac OS Catalina.
JDK 11 certification: https://www.oracle.com/java/technologies/javase/products-doc-jdk11certconfig.html
JDK Certifications: https://www.oracle.com/java/technologies/javase-subscription/documentation.html#sysconfig
When I only had JDK 14 installed, it wouldn't run. It looked like it was going to, but wouldn't even start. You will need to give permission for it to run as it is still not an Apple approved app. (Ctrl-click, then Open, supposedly works & saves your setting, but after so many changes trying to get this to work, I can't promise).