tkinter中将Entry输入框值转为整数触发ValueError报错如何解决

错误原因 #

代码执行顺序不符合Tkinter界面程序的运行逻辑，sample_value = int(e.get()) 这行代码在界面初始化阶段就会执行，此时输入框还未接收任何用户输入，e.get() 取到的是空字符串''，空字符串无法被转换为十进制整数，因此抛出ValueError。

修复方案 #

将读取输入框内容、转换为整数的逻辑移动到计算按钮的点击触发函数onclick内，保证只有用户点击按钮、已经完成输入后才会读取输入框内容。同时可以增加输入合法性校验，避免用户输入非数字内容时程序报错。

修正后完整代码 #

from tkinter import *
root =Tk()
root.title("Carbon Emission Calculator")
root.geometry("2560x1600")

#main title
main_title = Label(root, text="Carbon Emissions from Zoom Calls", font="Arial 25").pack(pady=75, padx=0)

#defining selections for radio buttons
x = IntVar()
y = IntVar()

#type of call
type_of_call = Label(root, text="Number of participants", font="Arial 20").pack(pady = 10)
Radiobutton(root,text= "1:1 call", variable= x, value=1).pack()
Radiobutton(root,text= "Group call", variable= x, value=2).pack()

#call quality
call_quality = Label(root, text="Call Quality", font="Arial 20").pack(pady = (40,10))
Radiobutton(root,text= "Default", variable= y, value=1).pack()
Radiobutton(root,text= "720p HD", variable= y, value=2).pack()
Radiobutton(root,text= "1080p HD", variable= y, value=3).pack()

#call duration
duration_of_call = Label(root, text="Duration of Call (in hours)", font="Arial 20").pack(pady = (40,10))
e = Entry(root, width = 10)
e.pack(pady = (0,40))

#calculations are here
#if (x.get() == 1):
    #if y.get = 

#submit button!
def onclick():
    input_content = e.get()
    # 输入合法性校验
    if not input_content.isdigit():
        Label(root, text="请输入合法的数字时长").pack()
        return
    sample_value = int(input_content)
    Label(root, text= sample_value).pack()

submit_button= Button(root, text="Calculate", command = onclick).pack()

root.mainloop()

内容的提问来源于stack exchange，提问作者dallenlee