Thanks for the quick and detailed answers. I will give Sweet Home 3D a try.

I have other applications that depend on Java, such as LibreOffice. If I uninstall Java before installing Sweet Home 3D, will other applications use the Java that comes with Sweet Home 3D?

Or are the two instances of Java independent?

When there is a new version of Java available (usually for security updates), is there anything related to Sweet Home 3D that I need to know?