如何引用对象

Question

我想在 App 类中从类 Screen 中选择一个对象。

我写了一个想要执行的命令，但它在代码中不起作用。我希望代码在应用程序关闭时触发。

main.py：

'''

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen

class Screeen(Screen):
    pass

class Manager(ScreenManager):
    pass

kv = Builder.load_file("plann.kv")
class Ball(App):
    #def on_stop(self):
        #print(Screeen.ids.textinput.text)

    def build(self):
        return kv

if __name__ == "__main__":
    Ball().run()

'''

plann.kv：

'''

Manager:
    Screeen:

<Screeen>:
    name: "Screeen"
    textinput: textinput
    FloatLayout:
        size: root.width, root.height
        TextInput:
            id: textinput
            text: "hi"
            size_hint: (.45, .1)
            pos: root.width * 1 / 3 , root.height * 1 / 2

'''

Answer 1

您应该添加收到的错误消息。无论如何，您需要先初始化类，然后再使用

.run()

方法，如描述 here

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen

class Screeen(Screen):
    pass

class Manager(ScreenManager):
    pass

kv = Builder.load_file("plann.kv")
class Ball(App):
    #def on_stop(self):
        #print(Screeen.ids.textinput.text)

    def build(self):
        return kv

if __name__ == "__main__":
    ball = Ball()
    ball().run()

我还建议将

v = Builder.load_file("plann.kv")

移到

build

方法中