Kotlin Null Safety

Null safety is one of Kotlin’s biggest value propositions. It pushes you to make absence explicit and handle it deliberately.

Nullable types

var name: String? = null

Safe calls

val length = name?.length

Elvis operator

val displayName = name ?: "anonymous"

Defensive design

Prefer non-null types by default and only use nullable types when the domain really allows missing values.

Practice

  1. Create one nullable variable and read it safely.
  2. Use the Elvis operator in one expression.
  3. Write one note about how null safety reduces production bugs.