In Java, there are also helper components, (a topic for future posts), but the integration is not as tight, so when we want to pass data into and out of Java we need to code somewhat more explicit to make data passing possible.
In our Java code, we need to represent the data passed in and out as class member column arrays. You define in your classes, one array per column passed in, and one array per column returned. These column arrays are some of the “magic” members I mentioned above, and they are the equivalent to
The components that are part of the Java extension need to know about these members as the components either populate them when pushing data into Java or read from them when returning data from Java. The way that the components know about the members is based on a naming standard.
It’s definitely easier to pass data in and get data back from R and Python, but I suppose part of that is Java being a static, compiled language.