AppEngine JDO cannot create a Persistent Object due to PMF

Question

I'm porting my api to Java from Python using AppEngine. I've decided to use JDO. I've created my model, and now I'm trying to create a new object that's persisted to the datastore.

I'm following the instructions here: https://developers.google.com/appengine/docs/java/datastore/jdo/creatinggettinganddeletingdata

Specifically, this code in the Making Objects Persistent section

    PersistenceManager pm = PMF.get().getPersistenceManager();

    Employee e = new Employee("Alfred", "Smith", new Date());

    try {
        pm.makePersistent(e);
    } finally {
        pm.close();
    }

The problem is, I don't know where PMF came from. I'm getting a "PMF cannot be resolved" error in Eclipse.

I've looked through other problems on SO to tease out PMF's origin, and found other people do this; PersistenceManagerFactory pmf;

But when I try that, I have a problem with get(). Eclipse is saying

The method get() is undefined for the type PersistenceManagerFactory

Does anyone have a complete example of creating a JDO object and persisting it to the datastore, with all the imports and necessary variables?

Thanks in advance!!!

Here's my code so far:

import java.io.IOException;
import javax.jdo.PersistenceManager;
import javax.jdo.PersistenceManagerFactory;
import javax.servlet.http.*;

@SuppressWarnings("serial")
public class Test_APIServlet extends HttpServlet {
    public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
        resp.setContentType("text/plain");
        resp.getWriter().println("Hello, world");
        PersistenceManagerFactory pmf;
        PersistenceManager pm = pmf.get().getPersistenceManager();
    }
}

Answer 1

You can read Google's doc at this link, which explains well enough what this PMF class is

https://developers.google.com/appengine/docs/java/datastore/jdo/overview-dn2

Scroll down to "Getting a PersistenceManager Instance" and there is the code. That is just one way of getting a PersistenceManagerFactory, and basic JDO doesn't need this class of Google's. Your code seems to have confused a real PersistenceManagerFactory with this wrapper class of Google's.