This is my questions

I am getting this message Exception in Tkinter callback

TypeError: 'str' object is not callable

How do I fix this

This is the code

# Import the required modules.

import tkinter

import tkinter.messagebox

import json

import random

class ProgramGUI:

def __init__(self):

# This is the constructor of the class.

# It is responsible for loading and reading the data from the text file and creating the user interface.

# See the "Constructor of the GUI Class of quiz.py" section of the assignment brief.

# Create the main window,

self.main_window = tkinter.Tk()

# set title to "Quiz"

self.main_window.title('Quiz')

# set default window size to width = 300 and hieght = 100

self.main_window.geometry('800x150')

self.main_window.configure(bg='skyBlue2', cursor='arrow')

self.main_window.resizable(width=False, height=False)

try:

# Open the file in read mode

f = open('data.txt', 'r')

# Read the json data into the 'data' variable

self.data = json.load(f)

f.close()

if len(self.data) < 5:

# Display the error message

tkinter.messagebox.showerror('Error','Insufficient Number of Questions')

# Destroy the main program

self.main_window.destroy()

return

except FileNotFoundError:

# Display the error message

tkinter.messagebox.showerror('Error','Missing/Invalid file')

# Destroy the main program

self.main_window.destroy()

return

except:

# Display the error message

tkinter.messagebox.showerror('Error','An Error has Occured')

# Destroy the main program

self.main_window.destroy()

return

self.question = random.sample(self.data, 5)

self.correct_answer = 0

self.current_question = 0

self.completed_questions = 0

self.score = 0

#GUI PROGRAM

#Create 3frames to gourp widgets

self.top_frame = tkinter.Frame(self.main_window)

self.middle_question_frame = tkinter.Frame(self.main_window)

self.middle_answer_frame = tkinter.Frame(self.main_window)

self.bottom_difficulty_frame = tkinter.Frame(self.main_window)

self.bottom_score_frame = tkinter.Frame(self.main_window)

#Create 3 frames to gourp widgets

self.top_frame.pack()

self.middle_question_frame.pack()

self.middle_answer_frame.pack()

self.bottom_difficulty_frame.pack()

self.bottom_score_frame.pack()

self.top_label= tkinter.Label(self.top_frame)

self.top_label.pack(side='top')

self.middle_question_label= tkinter.Label(self.middle_question_frame)

self.middle_question_label.pack(side='top')

self.middle_answer_entry= tkinter.Entry(self.middle_answer_frame, width = 20)

self.middle_answer_button= tkinter.Button(self.middle_answer_frame, text = "Submit Answer",bg='skyBlue2',command = lambda:self.check_answer())

self.middle_answer_entry.pack(side='left')

self.middle_answer_button.pack(side='left')

self.bottom_difficulty_label= tkinter.Label(self.bottom_difficulty_frame)

self.bottom_difficulty_label.pack(side='top')

self.bottom_score_label= tkinter.Label(self.bottom_score_frame)

self.bottom_score_label.pack(side='top')

self.show_question()

tkinter.mainloop()

def show_question(self):

# This method is responsible for displaying the current question and some other messages in the GUI.

self.middle_answer_entry.delete(0,'end')

self.current_question =self.current_question + 1

self.show_question =self.question[self.current_question]['Question']

self.top_label.configure(text = 'Question {}/{}'.format(self.current_question,5),bg='skyBlue2')

# if difficulity is greater or equal to 4 show a message

if self.question[self.current_question]['Difficulty'] >= 4:

self.bottom_difficulty_label.configure(text= 'This is a hard one',bg='skyBlue2')

else:

self.bottom_difficulty_label.pack_forget()

#Display Question

self.middle_question_label.configure(text = self.show_question, bg='skyBlue2')

self.bottom_score_label.configure(text = 'Good luck!', bg='skyBlue2')

self.completed_questions = self.completed_questions + 1

#Set Textbook to enter answers

text_entry =self.middle_answer_entry.focus()

return text_entry

def check_answer(self):

# This method is responsible for checking if the user's answer is correct when the button is clicked.

check_answer = self.middle_answer_entry.get().strip()

if len(check_answer) == 0:

# Display the error message

tkinter.messagebox.showerror('Error= invalid Input','Please enter an answer')

return check_answer

if check_answer in self.question[self.current_question]['Answer']:

self.correct_answer = self.correct_answer + 1

self.score = self.score + (self.question[self.current_question]['Difficulty']*2)

tkinter.messagebox.showinfo('Correct','Good job- you got it right!')

else:

tkinter.messagebox.showinfo('Incorrect',"The anwer is Incorrect")

if self.completed_questions == 5:

tkinter.messagebox.showinfo('Final Score','Game Over Final Score : {} Thank you'.format(self.score))

self.main_window.destroy()

else:

self.show_question()

gui = ProgramGUI()