Hi Jack, and thank you Ratslinger for the advice provided in your various posts to help users with similar questions.
I am a new user of LibreOffice, having downloaded it today (14 June 2018). I would describe myself as a fairly experienced user of a Mac, and a very experienced researcher of online information, but I find LibreOffice’s documentation, both in the help documents, its FAQ, its installation guides and so on to be appalling for this basic bit of functionality that is essential to make the Base (database) part of LibreOffice function properly. It was only on searching this knowledgebase for ‘Mac Java’ that I found any sensible answers, and this still required clicking through multiple answers from the very kind and patient Ratslinger. If I didn’t know better, I would get the impression that the creators and maintainers of LibreOffice are not interested in attracting Mac users to use the product.
I am on a 2017 iMac running Mac OS High Sierra (OS version 10.13.5) and I installed LibreOffice version 6.0.4.
After installing LibreOffice - since you will probably have done that before reaching this page - you need to install Oracle’s Java Development Kit, or JDK.
NOTE: The JDK is different from Oracle’s Java Runtime Environment or JRE. If you only install the JRE, the database module of LibreOffice will not function properly, and when you manually try to add the JRE to LibreOffice through the application’s preferences, you will fail.
Quit LibreOffice, if it is running.
Go to Oracle’s web page for the Java Development Kit or JDK. The current (as of 14/6/18) version is 10.0.1 and it can be found here: http://www.oracle.com/technetwork/java/javase/downloads/jdk10-downloads-4416644.html
On that page, click on the radio button for ‘Accept License Agreement’
On the same page, click on the link to download the version of the JDK for Mac OS.
After the disk image file has downloaded, double-click on it to mount the disk image.
Double-click on the icon for the installer package, and when prompted enter the user name and password for an account that has administrator privileges on the Mac. (If it is just your machine, this is the account name and account password you chose when you first set up your Mac.) Then click on the ‘install software’ button and whatever buttons are needed to enable you to install software downloaded from the web instead of Apple’s App Store.
Launch LibreOffice. Navigate to the preferences window (“LibreOffice” menu in the top left corner of the screen, then ‘Preferences’). Select ‘Advanced’ from the list of options on the left hand side. This should display the preference options for Java. If the installation of the JDK has gone well, it should already have a tick in the option for ‘Use a Java runtime environment’. In the pane below that, a radio button should indicate that the vendor is Oracle Corporation and then display the version number in the next column. As of 14 June, the version is 10.0.1.
Optional - If there is no Java package selected, you can add it manually. Click on the ‘Add’ button on the right hand side of the preference window. A normal Mac OS file dialogue box will open. Using that, navigate to the top of your Mac’s hard disk. This should list the following folders: Applications, Library, System, Users. Select ‘Library’. In the Library folder select ‘Java’, then ‘JavaVirtualMachines’. Within that, select the most recent (probably only) version of the JDK (currently ‘jdk-10.0.1.jdk’). Then, within that ‘Contents’, then ‘Home’. Then press the ‘Open’ button on the MacOS dialogue box to select that as the location.
Click on ‘OK’ in LibreOffice’s preferences to close them.
You should now be able to create databases in the Base part of LibreOffice.
I hope this helps you and other users. Again, my thanks to Ratslinger for his previous posts and help to other people using a Mac who wandered into this nightmare of a user experience.
PS Please click on the tick button (to the left at the start of this answer) if you found this helpful. Thanks!