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A simple table editor with formula support build in Java & Swing

By Teodor Neagoe

Getting Started

0. Prerequisites

• Java 21 or higher

1. Clone the repository

git clone https://github.com/Teoneag/Table-Editor

2. Build & run

You can run it directly from gradle

./gradlew run

Or alternatively, first build it

./gradlew build

And then run it

java -jar app/build/libs/app.jar

Or you can use IntelliJ IDEA to run it. (open the project and run the App class)

3. Enjoy!

⚠️ Don't forget to add = before the formula in the cell, just like in Excel! ⚠️

Features

File management

• create new table with custom size
• save table as CSV
• open table from CSV

Table

• cells can hold
  • normal text
  • formulas
    • the result of the formula is displayed
    • just double click it to edit it and you can see the formula
• move, resize columns

Formulas

• Parentheses: ()
• Binary operators: +, -, *, /, %, ^
• Unary operators: - (negation)
• Named functions with variable nr of args: pow, sqrt, abs, log, log10, exp, sin, cos, tan, min, max, sum, avg
• References to table cells: A1, ZZ3
  • live formula update (when you change a cell, all cells that depend on it are updated)
• the design is very modular, so it's easy to add new functions or operators

Design choices

• Save data: CSV
• UI
  • AppBar
    • File
      • New
        • Select rows and columns
      • Open
      • Save
      • Save As
      • Exit
    • Edit
      • Undo
      • Redo
      • Cut
      • Copy
      • Paste
    • Table
      • Insert Row
      • Insert Column
      • Delete Row
      • Delete Column
    • Help
      • About
  • Table
    • Show all saved ros and columns
    • Before any row, column: "-" button to delete
    • Between any row, column: "+" button to insert
    • See the result of any cell, when selected show the formula
    • If it's between "" it's text, otherwise it's a formula
    • If the formula is invalid, show an error message as a pop-up
• For decimal numbers use comma: 1,5
• calculating equation
  • tokenizer
  • parser AST
  • evaluator

Task

Write a table editor with formula support.

• Language: Java
• UI framework: Swing
• Requirements
  • edit a cell directly in the cell itself (not like Excel where you have a separate input field)
  • optional: select/edit multiple cells at once
• Formulas (write parser myself)
  • parentheses
  • binary operators
  • unary operators
  • named functions
• references to table cells

Example:

pow(-2, A1 - 3) * (42 + B2)

• My choice: set of supported operators, functions names

Grading

• the completeness of the implementation (the application should behave correctly with any user actions and any user input in the table cells)
• code quality (assume we will have to develop and maintain this project for a long time)
• simple, tidy interface (not expected a particularly beautiful UI)

Plan -> Actual: 6:24h

Chronological order. Planned time -> actual time

• read + make initial plan: 30m -> 34m
• swing example from GeeksForGeeks: 20m -> 5m
• read similar projects: 20m -> 21m
  • https://github.com/japplis/Joeffice
• Sketch UI: 10m -> 11m
• UI in Swing: 30m -> 2:30h
• Formula parser & evaluator: 3h -> 5h
  • https://en.wikipedia.org/wiki/Shunting_yard_algorithm
  • fix comma in cell: 10m -> 20m
  • https://www.geeksforgeeks.org/expression-evaluation/
• test, fix & write tests: 3h -> 2h:38m
  • allow strings in cells, fix empty cell: 13m
  • make formulas auto update: 20m
  • not happened: fix infinite recursion if happens (a=b, b=a)
  • make table full screen: 1m
  • show row numbers: 20m
    • https://stackoverflow.com/questions/64867515/how-to-add-row-header-in-table
  • make open file work: 1:10h
  • refactor: 34m
  • fix create a new table pop up: if you change a value, and the other one is wrong, when u are asked again for the values, the good one is lost
  • refactor table: 1h
• documentation & push: 30m -> 30m

ToDo

• bonus: multiple cells: 1h
• style: 1h
• final testing + fix todos: 1h
• when editing a cell, if you click on another cell, add that string to the current cell
• if trying to open invalide file, show its contents and suggest fix
• resize (add, remove cols)
• icon
• shortcuts (pressing esc on a cell should cancel the edit)
• implement the following
  • Comparison (==, !=, <, >, <=, >=)
  • Logical AND (&&)
  • Logical OR (||)
  • Logical NOT (!)
  • if(condition, value_if_true, value_if_false) - Returns one of two values depending on the condition.
  • concat(string1, string2, ...)
• select column when clicking on the name
• theme changing
• import, export to excel