Tkinter：通过按下按钮更新标签的值

Question

每次按下特定按钮时，都需要更新标签的值。但root.update（）不起作用，而且，我没有找到任何信息如何更新标签或至少整个GUI形式来获得新的值！那么，有人可以帮助吗？ 下面是代码：

from tkinter import * 
import random 
import decimal 

# random numbers 
random1 = decimal.Decimal(random.randrange(-155, 548))/100 
random2 = decimal.Decimal(random.randrange(-155, 548))/100 


root = Tk() 
root.title("Cheking numbers") 
root.geometry("640x480") 
root.resizable(width=False, height=False) 


# creating click event function 
def ResultFunction(): 
    if random1 - random2 > 1.30: 
     ResultLabel.configure(text='Result:' + str(random1 - random2)) 
    elif random1 < - 0.80 and random2 > -0.80: 
     ResultLabel.configure(text='Result:' + str(random1)) 
    elif random1 > - 0.80 and random2 < -1.30: 
     ResultLabel.configure(text='Result:' + str(random2)) 
    elif random1 < -0.80 and random2 < -1.30 and random1 < random2: 
     ResultLabel.configure(text='Result:' + str(random1)) 
    elif random1 < -0.80 and random2 < -1.30 and random1 < random2: 
     ResultLabel.configure(text='Result:' + str(random2)) 
    else: 
     ResultLabel.configure(text='Result: 0') 


# creating function for refreshing labels 
def RefreshLabels(): 
    root.update() 


# Labels 
Number1Label = Label(root, text=str(random1), font='georgia 20') 
Number1Label.pack() 


Number2Label = Label(root, text=str(random2), font='georgia 20') 
Number2Label.pack() 


ResultLabel = Label(root, text='Result:', font='georgia 20') 
ResultLabel.pack() 


# Buttons 
ResultButton = Button(root, text='Result', width=5, height=1, bg='white', fg='green', font='georgia 20', command=ResultFunction) 
ResultButton.pack() 


NextButton = Button(root, text='Next', width=6, height=1, bg='white', fg='green', font='georgia 20', command=RefreshLabels) 
NextButton.pack() 



mainloop() 

Answer 1

你ResultLabel是越来越单击ResultButton每一次更新，但好像没有任何反应，因为相同的随机值习惯于每次。所以你需要每次生成一对新的随机数。

我简化了你的程序，并且改变了名字以符合PEP-0008风格指南。我也用更明智的东西取代了可怕的“明星”导入。

这个任务不需要高精度的十进制数，简单的浮点数就足够了。

在您的ResultFunction中，最后两个elif子句具有完全相同的条件。我认为这是一个错字，所以我将第二个改为我认为你想要的。 ）

import tkinter as tk 
import random 

root = tk.Tk() 
root.title("Checking numbers") 
root.geometry("320x200") 
root.resizable(width=False, height=False) 

def show_result(): 
    random1 = random.randrange(-155, 548)/100 
    random2 = random.randrange(-155, 548)/100 

    number1_label.configure(text=str(random1)) 
    number2_label.configure(text=str(random2)) 

    if random1 - random2 > 1.30: 
     v = random1 - random2 
    elif random1 < -0.80 < random2: 
     v = random1 
    elif random1 > -0.80 and random2 < -1.30: 
     v = random2 
    elif random1 < -0.80 and random2 < -1.30 and random1 < random2: 
     v = random1 
    elif random1 < -0.80 and random2 < -1.30 and random2 < random1: 
     v = random2 
    else: 
     v = 0.0 

    result_label.configure(text='Result: {:.2f}'.format(v)) 

font = 'georgia 20' 

# Labels 
number1_label = tk.Label(root, text='', font=font) 
number1_label.pack() 

number2_label = tk.Label(root, text='', font=font) 
number2_label.pack() 

result_label = tk.Label(root, text='', font=font) 
result_label.pack() 

# Buttons 
result_button = tk.Button(root, text='Result', width=5, height=1, 
    bg='white', fg='green', font=font, command=show_result) 
result_button.pack() 

# Initialize 
show_result() 

root.mainloop() 

---

这个版本有两个按钮。 “下一步”按钮生成&显示一对新的随机数，它也清除“结果”标签。 “结果”按钮执行计算&显示结果。

import tkinter as tk 
import random 

root = tk.Tk() 
root.title("Checking numbers") 
root.geometry("320x240") 
root.resizable(width=False, height=False) 

random1 = random2 = 0 

# 'Next' button callback 
def do_randoms(): 
    global random1, random2 
    random1 = random.randrange(-155, 548)/100 
    random2 = random.randrange(-155, 548)/100 

    number1_label.configure(text=str(random1)) 
    number2_label.configure(text=str(random2)) 
    result_label.configure(text='Result:') 

# 'Result' button callback 
def show_result(): 
    global random1, random2 

    if random1 - random2 > 1.30: 
     v = random1 - random2 
    elif random1 < -0.80 < random2: 
     v = random1 
    elif random1 > -0.80 and random2 < -1.30: 
     v = random2 
    elif random1 < -0.80 and random2 < -1.30 and random1 < random2: 
     v = random1 
    elif random1 < -0.80 and random2 < -1.30 and random2 < random1: 
     v = random2 
    else: 
     v = 0.0 

    result_label.configure(text='Result: {:.2f}'.format(v)) 

font = 'georgia 20' 

# Labels 
number1_label = tk.Label(root, text='', font=font) 
number1_label.pack() 

number2_label = tk.Label(root, text='', font=font) 
number2_label.pack() 

result_label = tk.Label(root, text='Result:', font=font) 
result_label.pack() 

# Buttons 
b = tk.Button(root, text='Next', width=6, height=1, 
    bg='white', fg='green', font=font, command=do_randoms) 
b.pack() 

b = tk.Button(root, text='Result', width=5, height=1, 
    bg='white', fg='green', font=font, command=show_result) 
b.pack() 

# Initialize 
do_randoms() 

root.mainloop() 

我已经使用全局变量来存储随机数。将GUI包装到类中并将随机数存储为GUI类实例的属性会更好。