Using Classes within the same named package in Java

Question

I am trying to create two classes A and B that exist within a named package named components. A is a public class Window and B is a public class Door which contains an instance of A. The issue is that when compiling B using

javac -classpath . Door.java

, B cannot find A.

I understand that I can make this code work in an unnamed default package with no import clauses however I want these files to exist within one named class so that they can be imported elsewhere.

I have demonstrated to myself that Door.java will compile if the package components; line is commented out from both files however I do want to have this as a package named components.

I have also tried using import components.Window; within B but this doesn't work either.

//class A
package components;
public class Window{
public void rollup(){}
public void rolldown(){}
}

//class B
package components;

public class Door{
    public Window window = new Window();
    public void open(){}
    public void close(){}
}

My current code shows this which demonstrates that package B currently cannot access package A.

Door.java:8: error: cannot find symbol
        Window window = new Window();
        ^

How do I fix this code to allow B to create an instance of A whilst being within the same named package?

You have to execute the command javac -sourcepath . components/Door.java in the parent of the folder that contains both classes. For example, if you have Project/components/Door.java, you have to run the command from the folder Project. — Daniel Campos Olivares
– Daniel Campos Olivares, Commented May 14, 2019 at 12:32
you can't just change the package name you need to move the classes into a directory called components as well — David
– David, Commented May 14, 2019 at 12:35

lealceldeiro · Accepted Answer · 2019-05-14 14:22:30Z

1

Taking as reference the following structure

/some/base/route/project/components
                          |- Window.java
                          |- Door.java

Then, running javac -classpath . components/Door.java (as well as javac components/Door.java) from /some/base/route/project should work.

Notice that you need to run the command from 1 level up the directory that begins conforming the fully qualified package name for the classes. This mean, if you run the command from within /some/base/route/project/components it will not work.

Lastly, adding import components.Window; in Door class is useless because Window was already visible in Door since both classes are in the same package and Window is declared as public.

edited May 14, 2019 at 14:22

answered May 14, 2019 at 12:22

lealceldeiro

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1 Comment

Didgeridude Over a year ago

Yep , perfect. Lesson learnt - I needed to call javac from a terminal in the directory above this. That's an interesting quirk of java to learn!

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