Android Design patterns

Code snippet for commonly used design patterns in Android using Kotlin

Builder pattern

A kind of pattern that we use to show alert dialog. Pro Tip : https://www.jetbrains.com/help/idea/replace-constructor-with-builder.html#replace_constructorBuilder_example

Singleton pattern

1. Using object keyword.
2. Using holder pattern
3. Using lazy initialization

MVVM (Android specialist) with LiveData (Android Jetpack)

Model - View - ViewModel

Model: This is where we write all our Business logic and data state. All the data classes of our application are considered as Model.

data class Person(name:String){}

View: A typical user interface. Inflated with the help of XML as layouts.

ViewModel: Act as a bridge between the Model and the View. Contains UI logics. Manage the UI related complexities like data loss due to screen orientation. Ref : https://developer.android.com/topic/libraries/architecture/viewmodel

Sample for MVVM with the following implementations

1. Standared Viewmodel approach
2. Viewmodel approach with params.

Concepts

• Inline Functions

  • Keyword : inline
    • Accept other functions, or lambdas, as arguments.
    • Function call overhead doesn't occur. -> usage of memory, time and other resources.
    • Time taken to run the code inside the fun is < calling a fun that contains code. (ns)
  • Keyword : noinline
    • Avoid the function being inline
  • Keyword : crossinline
    • Help us to avoid the "non-local returns".

• Generics basics

  • Keyword : reified