App Inventor Interoperability

Accessing components

You can refer to a component by it's Designer name, such as Button1. Then you may call it's functions, set properties or listen to Events.

Functions and Properties

// show a simple toast usin the Notifier component
Notifier1.ShowAlert("Hello, World!")
// join the list elements and set to Label1's Text
let names = makeList("App", "Inventor")
for (name in names) {
    Label1.Text(Label1.Text() + name)
}

Events

You can also listen to a component's event!

// listening to Button1's Click
Button1:Click {
    // show a toast when Button1 is clicked
    Notifier1.ShowAlert("Why did you click me?")
}

If the event has parameters:

Notifier1:AfterChoosing(choice: String) {
    // do someting!
    Notifier1.ShowAlert("You choose " + choice)
}

Lookup components

You can query for components using with a string.

let acceptButton = get("Button1")
acceptButton.Text("Hello, World!")

Query many components with regex filter:

// Query for components whose name matches Button{number} format.
// The second argument specifies the type must be a button (java class simple name)
let myButtons = search("Button//d+", "Button")

Call a procedure

You can also call an App Inventor procedure!

let result = procedure("myProcedureName", arg1, arg2...)
Notifier1.ShowAlert("Procedure returned: " + result)

Control Calls

openScreen(name: String) - Opening a screen
closeScreen() - Closes current screen
closeApp() - Closes the application
startValie() - Returns start value as a String

Basic SyntaxJava Interoperability