Build an intent An Intent is an object that provides runtime binding between separate components, such as two activities. The Intent represents an app’s intent to do something. You can use intents for a wide variety of tasks, but in this lesson, your intent starts another activity. In MainActivity, add the EXTRA_MESSAGE constant and the …
Question Mark in Kotlin
While I am learning Kotlin, I notice some variables appended by a question mark. It is not common in other programming languages, so I do some search and got answer from Google. In Kotlin, programmer could express nullability explicitly in the type of a variable. By appending a question mark to the type, we let …