How to find out eclipse root path ?

import java.io.File;
public class EclipseRootPath {
public static void main(String[] args) {
// TODO Auto-generated method stub
System.out.println(new File("").getAbsolutePath());
System.out.println(new File(".").getAbsolutePath());
System.out.println(System.getProperty("user.dir"));
}
}