如何更新Tkinter标签？

Question

I have a simple tkinter GUI with a label displaying a number and a button. I have it set to the variable x, and when button is pushed, the value of x goes up by one. However, when I hit the button, the label doesn't update. How do I do this?

from tkinter import *

x = 1
def add():
    global x
    x += 1

win = Tk()

label = Label(win, text=x)
label.pack()

button = Button(win, text="Increment", command=add)
button.pack()

win.mainloop() 

Answer 1

Configuring the text of a label is a one shot effect. Updating the int later won't update the label.

To solve this, you can either explicitly update the label yourself:

def add():
    global x
    x += 1
    label.configure(text=x)

... Or you can use a tkinter variable like an IntVar (or more generally, a StringVar , if your text isn't just a number), which does update the label when you update the var. Don't forget to configure textvariable instead of text if you do this.

from tkinter import *

win = Tk()

x = IntVar()
x.set(1)
def add():
    x.set(x.get() + 1)

label = Label(win, textvariable=x)
label.pack()

button = Button(win, text="Increment", command=add)
button.pack()

win.mainloop()

Take care to create a Tk() instance before you create the IntVar , otherwise tkinter will throw an exception.

Answer 2

You have to do it manually by associating a command with the click of the button. Suppose you want the text of the Label to update when you click button :

button = Button(win, text="One", command=add) # add() is called when button is clicked

Now, you define the add command/function in order to change the text in the label:

def add():
    global x
    x += 1
    label.config(text=x) # calling the method config() to change the text

Answer 3

What I did is to use a IntVar() and a method to add or subtract:

*outside the class body*
def plus1(self,var,l):
    var.set(int(var.get())+1)
    l.textvariable = var
    return var.get()

*Inside the body of your class*
self.your_text = IntVar()
self.your_text.set(0)

self.l = Label(master, textvariable = (self.your_text))
self.plus_n = Button(root,text = '+',command=lambda : self.your_text.set(self.plus1(self.your_text,self.l) ) 

This is how I did it and it works for me, probably there are more elegant ways to solve the problem