在Eclipse中进行调试：找不到源

Question

I have a little project (guestbook, google example in java appengine documentation). https://developers.google.com/appengine/docs/java/gettingstarted/creating In this little project i had a problem when i want to do a debug step by step (F5). The step into doesn't work and i get a message in eclipse "source not found" with a button "edit source lookup path".

it seems the problem is known because i found similar posts on stack overflow but i didn't find solution for my case and the solution are sometimes quite different (ok ok i keep open minded). It seems there is a problem with the class path if i read this post.

In this post (the most complete i found on the topic) there are many things that i tested. Eclipse java debugging: source not found

For example, i have changed the definiton in preference>java>installed JRE but it is the same result... I have tried to create a new debug configuration too and many other things in this window. I need help to understand and configure Eclipse, hoping do not have break all my eclipse installation with my different test... tonight i have taken the decision to install a fresh copy of eclipse... but same results....

I have the conf below... eclipse keepler Release 1 google plugin for eclipse 3.5.1 appengine-java-sdk-1.8.8

thanks by advance for your help

edit 15.01.2014

the code is almost the same as google code. In debug mode, the perspective view is open when i get http://localhost:8888/guestbook , the breakpoint is highlighted and if i press F5, i get the error message "source not found" with the button.

package com.example.Guestbook;
import java.io.IOException;
import javax.servlet.http.*;

public class GuestbookServlet extends HttpServlet {

    @Override
    public void doGet(HttpServletRequest req, HttpServletResponse resp)  throws IOException {
        resp.setContentType("text/plain");
        resp.getWriter().println("Hello, world 1");
        resp.getWriter().println("Hello, world 2");
        resp.getWriter().println("Hello, world 3");

        resp.getWriter().println("breakpoint here " + this.myFunction()); // the breakpoint is here
    }


    // this method is not in the original google example
    public int myFunction(){
        int i=10;
        return i;
    }   
}

Answer 1

I sometimes trigger the same error, but there is often a way to avoid it. The solution in Eclipse is to use F6 (Step Over) instead of F5 (Step Into). Your breakpoint is probably on a line that calls code in a library outside of your project and it is the library whose source is unavailable. You don't want to step into the external library source code.

In your source code example, if you cannot single step from the line containing "breakpoint here " when it breaks there, try adding an additional breakpoint on the line containing "int i=10;" and then pressing F8 (Resume) instead.