小编Poo*_*dra的帖子

应用代码：

from kivy.app import App
from kivy.lang import Builder
from kivy.factory import Factory
from kivy.uix.screenmanager import Screen
from kivy.uix.screenmanager import ScreenManager
from kivy.uix.screenmanager import FadeTransition<br/>
kv = '''
ScreenManagement:
    transition: FadeTransition()
    screen1:
    screen2:
<screen1>:
    name: 'one'
    Button:
        text: 'Hello!'
        on_release: app.root.current = 'two'
<screen2>:
    name: 'two'
    Button:
        text: 'Hello2'
        on_release: app.root.current = 'one'
'''<br/>
class screen1(Screen):
    pass
class screen2(Screen):
    pass
class ScreenManagement(ScreenManager):
    pass
class test23(App):
    def build(self):
        return Builder.load_string(kv)
        <br/>
if __name__ == '__main__':
    test23().run()

每次我执行它时，我都有以下回溯。它出什么问题了？

 runfile('/home/pc/python and kivy/test23.py', wdir='/home/pc/python …