I found this tutorial (Adobe Experience Manager Help | Using Granite DataSource objects to populate AEM Touch UI objects ) and it uses JSP to populate a dropdown list in page properties.
Is it possible to do something similar with Java classes? Perhaps you can link me a tutorial? I've looked around and found nothing.
aem63app-repo/HelloWorldCompDDServlet.java at master · arunpatidar02/aem63app-repo · GitHub
You can use data source object for populating dropdown using HTL sightly.
See this HELPX article: Adobe Experience Manager Help | Using an WCMUsePojo class to populate an Experience Manager Touch UI...
Hope this helps!!
This is for getting the property, you can set them as well: Adobe Experience Manager Help | Using an WCMUsePojo class to populate an Experience Manager Touch UI...
Reference post:-Is it possible to access pageProperties from a datasource?
how to add values to multi valued properties using JSP