Context for Toast in JetPack Compose | Android

Let’s have a look at the arrow button in the image below 👇, we want to click it and show a Toast message in response to this user engagement.

Let’s begin

Toast.makeText(this, "This is a Toast Message !", Toast.LENGTH_SHORT).show().

We will encounter an error ‘this ’ is not defined in this context when called form a non composable function; although it will work fine in Java and Kotlin but not in Jetpack Compose.

When called from a Non Composable function

Following error will be thrown
❌ this ’ is not defined in this context

fun simpleToastMessage(context: Context) {
    Toast.makeText(this, "This is a Toast Message !", Toast.LENGTH_SHORT).show()
}

(this) keyword will be underlined in red color indicating an error.

When called from a Composable function

@Composable
fun simpleToastMessage(context: Context) {
    Toast.makeText(this, "This is a Toast Message !", Toast.LENGTH_SHORT).show()
}

❌ Same will happen in composable when we call context directly with this keyword.

Now let replace this keyword with LocalContext.current 👇

@Composable
fun simpleToastMessage() {
     Toast.makeText(LocalContext.current, "This is a Toast Message !", Toast.LENGTH_SHORT).show()
}

Following error will be thrown
❌@Composable invocations can only happen from the context of a @Composable function

✅Correct Way !

val context = LocalContext.current

Whether we call context from composable or non composable does not matter, we just need to declare and initialize context variable at the start of the function.

@Composable
fun simpleToastMessage() {
    val context = LocalContext.current
    Toast.makeText(context, "This is a Toast Message !", Toast.LENGTH_SHORT).show()
}

The Toast.makeText() method requires three parameters:

1. Context object: You need to pass the application context or the Activity context.
   - Using LocalContext.current we can get the Context object.
   - LocalContext.current can be used only from within a Composable function. Such as we are using it within Column() function which is a composable function. LocalContext.current cannot be used within a function which is not marked with @composable annotation.

2. Message (CharSequence as String): You have to pass the message to be displayed in Toast.

3. Duration (int): Pass duration as Toast.LENGTH_SHORT or Toast.LENGTH.LONG to display Toast for shorter and longer duration on screen.