class_filedialog.py

from tkinter import *
from tkinter import filedialog

class App(Tk):
	def __init__(self):
		super().__init__()

		# Title, icon, size
		self.title("Tkinter.com - OOP File Dialog")
		self.iconbitmap('images/codemy.ico')
		self.geometry('700x450')

		# Create Widgets
		self.my_text = Text(self, width=80, height=20)
		self.my_text.pack(pady=20)

		self.my_button = Button(self, text="Open File", command=self.file)
		self.my_button.pack(pady=20)



	# Create Popup Function
	def file(self):
		self.my_file = filedialog.askopenfilename(initialdir="", 
			title="Select a File",
			filetypes=(("txt files", "*.txt"), ("All Files", "*.*")))
		
		# Check to make sure user selected a file
		if self.my_file:
			# Open and read the file
			get_contents = open(self.my_file, "r")
			self.my_text.insert(END, get_contents.read())


# Define and instantiate our app
app = App()
app.mainloop()