CODEWITHSUNDEEP
javaimportpackage
user2911290
user2911290

Reputation: 1406

How to access a class whose .java file has no package statement?

I'm just curious about something. Say I have the following environment:

Folder structure -

projects \ prj1 \ src \ pkgs \ main (contains Main.java)
                             \ test (contains TestClass.java)

Main.java -

package pkgs.main;

import pkgs.test.TestClass;

class Main {
    public static void main(String[] args) {
        TestClass tc;
    }
}

Java shell based compilation commmands -

javac -d ..\cls -sourcepath ..\src ..\src\pkgs\main\Main.java
java -classpath ..\cls pkgs.main.Main

If I then make a .java code file called Default.java, that doesn't have a package statement -

public class Default {}

and place this file in the src folder, how can a class file such as Main.java access this Default class? I tried using the following import statements, but neither worked, causing compilation errors:

Main.java -

package pkgs.main;

// import Default;    (causes many compilation error messages)
// import .Default;   (causes "identifier expected" compilation error)

I also moved the Default.java file from the src folder, in to the same folder that contained Main.java, but that didn't work either. I appreciate that this whole idea seems like bad design, but I'm only doing it in order to learn a bit more about how the package and import statements work, alongside the project folder structure. Thanks.

Upvotes: 3

Views: 4702

Answers (1)

Evgeni Sergeev
Evgeni Sergeev

Reputation: 23593

To avoid two steps of indirection, the essence of the accepted answer is that according to the specification:

It is a compile time error to import a type from the unnamed package.

Which means that if you're not in the unnamed (aka default) package, you can't reach classes in the unnamed/default package, unless you are prepared to turn to reflection.

However, if you're in the unnamed/default package, you don't need to import anything, just don't forget to set the classpath, e.g. javac -cp "." ABC.java

Upvotes: 3

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