import class/package placed in another package of same/higher level of hierarchy

Question

I have two folders pack1 and pack2 in my desktop. pack1 contains file1.java file and the code is:

public class File1 {
    public static void main(String[] args){     
    }   
}

and pack2 contains file2.java and the code is:

import pack1.File1;
public class File2 {
    public static void main(String[] args){     
    }   
}

I successfully compiled file1.java and file1.class is created in pack1 but I got error while compiling file2.java:

error: package pack1 does not exist
import pack1.File1;
            ^
1 error

from the above error what I thought is I can only import class/package which are present in same or sub-directories because Pack1 is not in the same directory in which I am compiling(current working directory = $HOME/Desktop/pack2) please correct me if I am wrong.

If my understanding is correct how can I import file1 in file2.

Answer 1

You have to understand:

• "the real" class name is always the.complete.package.WhateverClass
• there is no concept of "sub packages".

Sure, from a directory perspective the classes for ab and a.c will all sit in folders within the a directory, but for anything inside ab , it still has to use the full name a.c.Whatever

Thus your import always look the same, like:

import com.pack1.subpack2.TheClass

In other words: when your code sits in ab , there is no difference in importing from a.c or xyz , you simply always give the full class name, with all the packages that belong to it.