Create a calculator application with App Inventor

Presentation of App Inventor

App Inventor is a visual, blocks-based programming language and online platform for creating mobile apps for Android devices. It was developed by MIT’s Media Lab and is now maintained by the Massachusetts Institute of Technology (MIT). It allows users with little or no programming experience to create their own mobile apps by dragging and dropping visual blocks that represent programming concepts. App Inventor is also open-source, which means that anyone can access, modify, and distribute the software. It is intended to help educators and students learn programming and is widely used in classrooms and educational institutions.

It is possible to create a calculator application using App Inventor. To do this, you would first need to design the user interface of the calculator using the built-in components such as Buttons and TextBoxes. You would then need to create event handlers for the various buttons using blocks. These event handlers would specify the behavior of the calculator, such as performing mathematical operations when the buttons are pressed.

To create the calculator‘s interface you can use a Layout manager, such as a HorizontalArrangement or a TableArrangement, to organize the buttons and Textbox. You can add Buttons for numbers and mathematical operations (e.g. +, -, *, /). A Textbox can be used to display the results of calculations.

Once the interface is set, you can proceed to set up the event handlers to make the calculator functional. you can use the blocks to specify the behavior of the calculator when the buttons are pressed. For example, when the user presses the « 1 » button, an event handler would be triggered that would add the number « 1 » to the current value in the TextBox. When the user presses the « + » button, an event handler would be triggered that would add the current value in the TextBox to a running total, and so on.

You can also include additional functionality to the calculator, such as a memory function (e.g. « M+ » and « M-« ) or a clear function (e.g. « C »).

It’s worth noting that, App Inventor doesn’t have a built-in functionality to perform complex mathematical operations such as trigonometry, logarithms, etc.

Purpose of this tutorial:

In this tutorial we will create a calculator application with App Inventor that does the following 4 operations: sum (+), product (*), subtraction (-) and division (/).

We propose to make a small simple calculator, with the following visual:

Calculator Application Programming

To program the application, App Inventor proposes to use The Space Blocks which allows to create a program in the form of a block diagram. Very simple to use but requires some programming logic.

Here is the calculator program realized in the Blocks space of the App Inventor: