Question

为什么screen.destroy（）抛出一个异常，屏幕是一个空对象？我按下按钮时试图更新我的屏幕标签，但它没有发生。

from tkinter import *

def buttonOne():
    num1.append("1")
    number = ""
    count = 0
    while count < len(num1):
        number = number + str(num1[count])
        count += 1
    screen1 = Label(text=number).grid(column=0, row=0)
    screen.destroy()

def main():
    window = Tk()
    window.title("Calculator")
    global num1
    num1 = []
    global screen
    screen = Label(text="0.0").grid(column=0, row=0)    
    button1 = Button(text="1", command=buttonOne)
    button1.grid(column=0, row=2)
    window.mainloop()

main()

Answer 1

你有问题因为你做了

screen = Label(text="0.0").grid(column=0, row=0)

并向None致screen因为grid() / pack() / place()返回None

你必须分两行

screen = Label(text="0.0")
screen.grid(column=0, row=0)

顺便说一句：您可以使用方法之一

替换标签中的文字

 screen["text"] = "new text"
 screen.config(text="new text")

见

def buttonOne():

    num1.append("1")

    number = ""

    for item in num1:
        number += str(item)

    screen["text"] = number

因为你只把字符串放在列表上然后你可以缩短

def button_one():

    num1.append("1")

    screen["text"] = ''.join(num1)

完整版

import tkinter as tk

def button_one():

    num1.append("1")

    screen["text"] = ''.join(num1)

def main():
    global num1
    global screen

    num1 = []

    window = tk.Tk()
    window.title("Calculator")

    screen = tk.Label(text="0.0")
    screen.grid(column=0, row=0)

    tk.Button(text="1", command=button_one).grid(column=0, row=2)

    window.mainloop()

main()

Answer 2

如果您遇到Nonetype错误，则必须将网格放在不同的行上。

from tkinter import *

def buttonOne():
    global screen
    num1.append("1")
    number = ""
    count = 0
    while count < len(num1):
        number = number + str(num1[count])
        count += 1
    screen1 = Label(text=number).grid(column=0, row=0)
    screen.destroy()

def main():
    global screen
    window = Tk()
    window.title("Calculator")
    global num1
    num1 = []

    screen = Label(text="0.0")
    screen.grid(column=0, row=0)
    button1 = Button(text="1", command=buttonOne)
    button1.grid(column=0, row=2)
    window.mainloop()

main()

一旦使用tkinter初始化我如何更新我的gui？

2 个答案: