根据 if 语句更改 Tkinter 标签文本？

Question

I am trying to create a simple GUI using Tkinter. I created a label with a text. This text should be changed when a button (physical) is pressed. I read about using the after() method, but it only runs a method ones, it should always check for user input.

while 1:
    root = tk.Tk()
    GPIO.setmode(GPIO.BCM)
    GPIO.setup(21, GPIO.IN, pull_up_down=GPIO.PUD_UP)
    input_state = GPIO.input(21)

    menutxt = tk.StringVar()
    menuLabel = tk.Label(root, textvariable=menutxt).pack()

    if input_state == False:
        menutxt.set("TEXT2")
    else:
        menutxt.set("TEXT1")
    root.mainloop()

Answer 1

You don't know what is a loop ? you can try with

root = tk.Tk()
menutxt = tk.StringVar()
menuLabel = tk.Label(root, textvariable=menutxt).pack()
GPIO.setmode(GPIO.BCM)
GPIO.setup(21, GPIO.IN, pull_up_down=GPIO.PUD_UP)
while 1:
    input_state = GPIO.input(21)
    if input_state == False:
        menutxt.set("TEXT2")
    else:
        menutxt.set("TEXT1")
root.mainloop()