Java Development Tools

I have a Java Standalone application. I created a Project in JDeveloper (10.1.3.3) J2EE Edition.

The Main class com.mycom.MainEntry.java needs to read a property file config/conf.properties. In the Java class, the file path is "config/conf.properties".
But when I run the class, I got error: file config/conf.properties cannot be found:
The files are in the following folders:

C:/sandbox/project1/com/mycom/MainEntry.java
C:/sandbox/project1/config/conf.properties

I created a project project1 in JDeveloper and the Java class was compiled and located under folder
... jdev/mywork/application1/project1/classes/com/mycom/MainEntry.
I also copied the property file to:
... jdev/mywork/application1/project1/classes/config/conf.properties

Can someone tell me where I should put the property file or how to configure the JDeveloper's project properties, so that the Java class can find the property file?

Thanks