Import class from other directory in Python

Question

For anyone interested: The easiest solution was

import sys
sys.path.append('../')

from Folder2.Folder2-1.File2 import Foo

---

I've got this structure:

Program:
    Folder1:
        __init__.py
        File1.py

    Folder2:
        __init__.py
        Folder2-1
            __init__.py
            File2.py

File1:

from .Folder2.Folder2-1.File2 import Foo
Foo().hello()

File2:

class Foo:
    def hello(self):
        print("Hello!")

I want to import the Foo class located in File2.py into File1.py. I've tried:

from .Folder2.Folder2-1.File2 import Foo That gives

  File "/data/user/0/ru.iiec.pydroid3/files/accomp_files/iiec_run/iiec_run.py", line 31, in <module>
    start(fakepyfile,mainpyfile)
  File "/data/user/0/ru.iiec.pydroid3/files/accomp_files/iiec_run/iiec_run.py", line 30, in start
    exec(open(mainpyfile).read(),  __main__.__dict__)
  File "<string>", line 1, in <module>
ImportError: attempted relative import with no known parent package

As you can see I'm on my phone because I'm not home right now. It should be the same as Linux tho. I added the __init__.py files because in other questions they were mentioned.

My actual structure for MD98s answer:

Desktop:
    Code:

        findPath:
            __init__.py
            findPath.py
            testFindPath.py #empty

        useful:
            __init__.py
            RSA:
                __init__.py
                RSA.py
                RSAresources.py

I would like to import the RSA class from RSA.py into findPath.py

So, if I had:

Desktop:
    Code:

        findPath:
            __init__.py
            findPath.py
            testFindPath.py #empty

        __init__.py
        useful.py

useful.py:

class RSA:
    def encript(self,msg):
        return 123456778

class Hash:
    def hash(self):
        return 1234456778

I would import Hash into findPath.oywith:

from .useful import Hash

Answer 1

I am confused by your folder structure, but normally you can import classes or methods like this, assuming the script you're writing is inside your project directory:

from foldername.filename import Foo

or

from folder name.foldername2.filename import Foo

I hope this helps you. Otherwise please be a little more precise about your folder structure.