[英]error in running a simple kivy program after uninstalling and installing python and pycharm error:raise Exception('Invalid instance in App.root')
from kivy.app import App
class mainWin():
pass
class helpApp(App):
def build(self):
return mainWin()
if __name__ == "__main__":
helpApp().run()
.kv 文件
<mainWin>:
name: "main"
GridLayout:
rows: 4
Label:
text: "How can we help you???"
Button:
text: "Walking assistant"
Button:
text: "Text to Speech"
Button:
text: "Speech to Text"
App
的build()
方法必须返回一个Widget
,它将成为App
的根。 但是您的build()
方法不返回Widget
。 或许:
class mainWin():
pass
和:
class mainWin(Screen):
pass
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