How deeply does Kotlin in Action, 2E cover default method?

Explains declaration, inheritance, conflicts, explicit overrides, and qualified super calls, but does not descend into generated JVM mechanics.

Default method

As explained in Kotlin in Action, 2E

A default implementation is a member implementation provided by an interface that implementing types can inherit without redefining it.

A default method is an interface function with a body. An implementing class may inherit that behavior instead of redefining it, while still implementing abstract interface methods. section 4.1.1

Providing and resolving default behavior

interface Clickable { fun click() fun showOff() = println("I'm clickable!") } interface Focusable { fun showOff() = println("I'm focusable!") } class Button : Clickable, Focusable { override fun click() = println("I was clicked") override fun showOff() { super<Clickable>.showOff() super<Focusable>.showOff() } } Button().showOff() // I'm clickable! // I'm focusable! A class may omit showOff when only one inherited default exists. When multiple interfaces provide that method, Kotlin requires an explicit override; the implementation can call either or both inherited versions with super<Type>.

How Kotlin in Action, 2E covers it

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Related concepts

natural language interfacepart of · A natural language interface enables interaction with a system through human-language text or speech.
interfacepart of · A software interface is a contract or boundary that specifies the operations, properties, or capabilities through which types or components interact, without requiring a particular implementation.
traitpart of · A trait is a type-level construct that defines reusable behavior or members that types can implement or compose.
static methodproduces · A static method is a function associated with a type or enclosing scope rather than an object instance, and callable without an instance receiver.
fluent interfaceused by · A fluent interface is an API design style in which operations return objects or values that enable readable chaining of subsequent calls.

This explainer was generated by Manning's knowledge graph from the text of Kotlin in Action, 2E. The section links point to the parts of the book it draws on.