why does python Kivy Boxlayout not show up when code is copied 100% from very recent tutorial?

Question

i'm following a youtube tutorial on kivy and in the first part i already stumble upon a problem i can't seem to solve or find anything about: BoxLayout does not show up, like not even an error it just doesn't seem to exist even though i made sure the code was 100% the same as in the tutorial, please help.

Python file:

    from kivy.app import App
    from kivy.uix.widget import Widget
    from kivy.uix.boxlayout import BoxLayout

    class BoxLayoutExample(BoxLayout):

    pass
    """def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.orientation = "vertical"
        b1 = Button(text="A")
        b2 = Button(text="B")
        b3 = Button(text="C")

        self.add_widget(b1)
        self.add_widget(b2)
        self.add_widget(b3)
        """


        class MainWidget(Widget):
            pass


        class TheLabApp(App):
            pass


        TheLabApp().run()`

KV File

    MainWidget:

<BoxLayoutExample>:
    orientation: "horizontal"
    size: root.width, root.height
    Button:
        text: "A"
        size_hint: .5, .5
        pos_hint: { center_x: .5 }
        color: 0, 0, 1, 1
    Button:
        text: "B"
    Button:
        text: "C"

<MainWidget>:
    Button:
        text: "Hello"
        size: "100dp", "80dp"
        pos: "100dp", "200dp"
        color: 0, 0, 1, 1
    Label:
        text: "Hello2"
        size: "100dp", "80dp"
        pos: "200dp", "200dp"
        color: 1, 0, 0, 1

Answer 1

the code looks a bit weird indentation wise, but probably your copy paste here, but did you name your kv file thelab.kv as required for it to be loaded automatically? (kivy looks for a kv file named like the app class, but lowercase, and without the "app" suffix).

Answer 2

Write BoxLayoutExample: at the top part of your kv file similar to how you wrote mainwidget: . After that it should work