How do I close the Flutter app?

In flutter, most widgets already come with an option to disable them for example in a RaisedButton we can set the onClicked function to null to disable , or we can use NeverScrollableScrollPhysics( ) to disable a ListView.

A Flutter package that allows Android users to press the back-button twice to close the app.

Flutter Screen Lock. This Flutter plugin provides an feature for screen lock. Enter your passcode to unlock the screen . You can also use biometric authentication as an option.