如何在KivyMD中点击按钮时更新MDLabel的文本内容

Hey there! Let's get that text updating working in KivyMD. Coming from tkinter, the approach is a bit different but super simple once you get the hang of it. Here's how to fix your code:

Key Changes Needed: #

• Call the app's function from KV language: Use app.change_word() in the button's on_press event—app refers directly to your running AnsweredOrNot app instance.
• Access the MDLabel via its ID: In your change_word method, you don't need extra parameters beyond self. Just use self.root.ids['text-update'] to grab the label (since your ID has a hyphen, dictionary-style access is safer; if you used underscores like text_update, you could use self.root.ids.text_update instead for cleaner syntax).
• Kivy auto-updates the UI: Unlike tkinter, you don't need to call an update() method—changing the label's text property will automatically refresh the display.

Modified Working Code: #

from kivymd.app import MDApp
from kivy.lang import Builder
import random
from kivy.core.window import Window
Window.size=(400,600)

please_anwser_this="""
MDScreen:
    MDLabel:
        id:text-update
        text:'Click The Button below to Change this text'
        halign:'center'
        pos_hint:{'center_x':0.5,'center_y':0.6}
    MDFillRoundFlatIconButton:
        text:'Change It'
        pos_hint:{'center_x':0.5,'center_y':0.5}
        icon:'crop-rotate'
        on_press: app.change_word()  # Trigger the text update function here
"""

class AnsweredOrNot(MDApp):
    def build(self):
        builder=Builder.load_string(please_anwser_this)
        return builder
    
    def change_word(self):
        # No extra parameters required besides self
        site_list=['Google','Yahoo','Microsoft','APKpure','APKMB','Stackoverflow','Bing']
        text=random.choice(site_list)
        # Access the label and update its text property
        self.root.ids['text-update'].text = text

AnsweredOrNot().run()

Quick Tip: #

For smoother ID access, try using underscores instead of hyphens in your widget IDs (e.g., text_update instead of text-update). This lets you write self.root.ids.text_update instead of the dictionary syntax, which feels a bit more intuitive.

内容的提问来源于stack exchange，提问作者ZARIR