Type? and Type!

Nullable and non-null reference type suffixes.

Type? marks a nullable reference; Type! marks non-null with compile-time checks. Plain Type is a platform type (Java-like, no enforced nullability). Assigning null to Type! is a compile error.

Affogato

var name: String! = "Alex"
var email: String? = null

// Compile error:
// var bad: String! = null

Generated Java

@dev.affogato.annotations.NotNull
String name = "Alex";
@dev.affogato.annotations.Nullable
String email = null;

Related

• name: Type — Type-after-name declaration syntax for parameters, locals, and fields.

See also

• Nullability

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