create a text box for the user to enter an integer between 3-6(inclusive)

there are two main component/criterias which need to be met in this assignment. this a javafx assignment which is to render a 2d shape based on an integer input by a user. component 1: create a text box for the user to enter an integer between 3-6(inclusive) . each number corrisponds to the number of sides the shape will have. i.e. the input ‘3’ will generate a 3sided shape i.e a triangle. if an integer outside the range of 3-6 is entered. this will produce an error. i have already done that. the second component states that a user can only increase/decrease the input the number of sides of the shape displayed on the scene by 1. this means if i.e a a user inputs an integer of ‘4’ which produces a 4 sided shape, he can only enter a ‘5’ or a ‘3’. otherwise an error will occur saying you can only increase’decrease by 1. also there can only be one shape on the screen. i.e if there is a triangle on the screen, and the user inputs an integer of ‘4’, a 4 sided shape would replace the triangle. I have already created the shapes and met the criteria for component 1. currently in my code, after a user inputs a valid number (3-6) the textbox needed for the user to input an integer dissapears. and I have a buttons to increase/decrease which do not work and are wrong. after the first input by the user/the first shape is drawn, i want the user to be able to have a textbox to enter another integer. however this integer should be limited to a decrease/decrease in the number of sides of the active shape by 1 after everyshape is drawn. i have attached by current code and the actual assignment instructions. please ignore the essay part. just do the coding aspect