What does it mean to delegate a property in Kotlin?
A “Delegate” is just a class that provides the value of a property and handles its changes. This will help us delegate (assign or pass), the entire getter-setter logic to a different class so that it can help us with code reuse. This is an alternative to the inheritance property.
Table of Contents
What are nullable types and non-nullable types in Kotlin?
Nullable Types and Non-Nullable Types Kotlin’s type system aims to eliminate the danger of null references from code, also known as The Billion Dollar Mistake. One of the most common mistakes in many programming languages, including Java, is that accessing a member of a null reference will result in a null reference exception.
Is there a null security guarantee in Kotlin?
Since Kotlin doesn’t have any information about the nullability of a declared type in Java, it relaxes compile-time null checks for these types. Therefore, he does not get any null security guarantees for types declared in Java, and he takes full responsibility for the operations he performs on these types. The compiler will allow all operations.
How does a by clause work in Kotlin?
The by clause in the list of supertypes for Derived indicates that b will be stored internally in Derived objects and the compiler will generate all methods of Base that forward to b. Overrides work as you expect: the compiler will use your override implementations instead of the delegate object’s.
Is it possible to initialize an object in Kotlin?
The Android component code using Kotlin could probably be written as: In the example above, there is no big problem if initialization is possible with object creation. However, you cannot declare and use a value in advance if you reference it after a specific initialization process because it has its own lifetime to initialize itself.
How are lazy and observable properties handled in Kotlin?
Lazy properties: the value is calculated only on the first access. Observable Properties: Listeners are notified about changes to this property. Store properties in a map, instead of a separate field for each property. To cover these (and other) cases, Kotlin supports delegate properties: Copied!
What are the advantages of migrating from Java to Kotlin?
Most Java developers are enjoying the migration from Java to Kotlin. Kotlin offers clean, concise, and efficient code. Also, it comes with many advantages. One of those advantages is the delegation of properties. What is the Delegation of Assets?
How does a lazy function work in Kotlin?
Lazy is a lambda function that takes a property as input, and in return provides an instance of Lazy, where is basically the type of properties you’re using. Let’s take a look at the following to understand how it works.
Where does the exception keyword go in Kotlin?
All exception classes descend from the Throwable class. Kotlin uses the throw keyword to throw an exception object. Although Kotlin inherits the exception concept from Java, it does not support checked exceptions like Java.
How to prevent properties from being overridden again in Kotlin?
If you want to prohibit overwriting, use final: Copied! Property overriding works similarly to method overriding; properties declared in a superclass that are later redeclared in a derived class must be preceded by override and must have a compatible type.
Can a member function override an extension function in Kotlin?
In Kotlin, extension functions cannot override member functions; furthermore, they are resolved statically. It implies that if you write a fun extension function Something.toString() =…, s.toString() will not resolve, because the member always wins.
When to use the open modifier in Kotlin?
The open modifier has no effect when added to members of a final class (that is, a class with no open modifier). A member marked as overridden is itself open, that is, it can be overridden in subclasses. If you want to prohibit overwriting, use final: Copied!
How to delegate a property to another property?
A property can delegate its getter and setter to another property. Such delegation is available for both top-level and class (member and extension) properties. The delegate property can be: To delegate a property to another property, use the appropriate :: qualifier in the delegate name, for example this::delegate or MyClass::delegate. copied!
How is delegation used in object oriented language?
Using Delegation, you can pass an object of another type, such as a subtype of class A, to an instance of B. This fact makes Delegation an extremely powerful mechanism. There are two types of delegation: Explicitly. It can be implemented in any object-oriented language. Implicitly. Requires language support for this feature.