kotlin guide

node of the layout file adds a custom namespace declaration, such as "xmlns:app=" Http://schemas.android.com/apk/res-auto "" and change the Android.support.v4.view.PagerTabStrip node name to the full path name of the custom view, such as "Com.example.custom.widget.PagerTab", At the same time, the new two attributes, App:textcolor and app:textsize, are specified under this node. The layout file code after the modification is as follows: The three steps of the custom attribute above, where the se

Forward pushDesign PatternsSimple Factory mode (Java and Kotlin Edition)Kotlin Basic KnowledgeKotlin first lesson: Starting with Java comparisonKotlin Introductory Lesson II: Collection OperationsKotlin Introductory Lesson Three: Data typesFirst attempt to implement Android projects with Kotlin1. DefinitionThe factory method pattern (Factory mode), also known as the factory pattern, is called the virtual Co

Using the Kotlin-kapt pluginRely on Java annotationprocessor instead of KAPTWhen using the control binding use, online search method, do not know by which guy with the pit.Error usage @BindView (r.id.tv_title) lateinit var tvtitle:textviewresult in the use of the control, there is no binding success, errorKotlin. Uninitializedpropertyaccessexception:lateinit property title had not been initializedCorrect useTv_title.settextcolor (color.red)Tv_title.s

Android-kotlin in fragment get ViewoverviewWhen using fragment, Butterknife was used to get the view but it went wrong, and then it was used to get the view directly using the Kotlin import layout, but it was wrong.ReasonThe reason is that the view is called in the Fragment Oncreateview method, which is obviously not possible because the view is not bound to the Fragment. So the initialization code can be p

1. ThreadJava notationNew Thread (New Runnable () {@Overridepublic void Run () {}}). Start (); Kotlin notationThread (Runnable { }). Start () 2, HandlerJavaPrivate Handler handler=new Handler (New Handler.callback () {@Overridepublic boolean handlemessage (Message msg) {Switch (msg.what) {Case 0:BreakDefaultBreak}return false;}}); KotlinPrivate Val Handler=handler (handler.callback{msg->When (Msg.what) {0->{}else->{}}False}) 3, SetonclicklistenerJavaB

Using Anko and Kotlin to develop databases on Android: SQLite is never an easy task (KAD25). ankokotlin By Antonio Leiva Time: Mar 30,201 7 Link: https://antonioleiva.com/databases-anko-kotlin/ The fact tells us that writing a database in Android is quite boring. When using SQLite, all the required templates are not the most pleasant thing in the world today. Fortunately, one of the items they announce

Examples of Spring Boot and Kotlin scheduled Tasks (Scheduling Tasks) and kotlinscheduling You may encounter such scenarios when writing Spring Boot applications. For example, you need to regularly send text messages, emails, and other operations, and you may also regularly check and monitor some labels and parameters. Create scheduled task Writing a scheduled task in Spring Boot is very simple. The following describes how to create a scheduled task i

function function Declaration Functions in Kotlin Use the FUN keyword declaration Fun double (x:int): Int { } function Usage Calling a function using the traditional method Val result = double (2) Call member functions using dot notation Sample (). Foo ()//Create class sample instance and call Foo infix notation Functions can also be called with infix notation when they are member functions or extension functions they have only one parameter

Before you read the following, you may need to understand some of the features of the Kotlin language: At the end of a statement, you can declare a method with the Fun keyword, and if the function is a method that overloads the parent class, you must also add the Override keyword. The parameter of the method is the first-write parameter name followed by the colon-and-write parameter type; The Kotlin source

A sealed class is used to represent a restricted class inheritance structure: When a value is a finite set ofType, and cannot have any other type. In a sense, they are extensions of the enumeration class: A collection of values for the enumeration typeis restricted, but there is only one instance of each enumerated constant, and the sealed classCan have multiple instances that can contain states. To declare a sealed class, you need to add the sealed modifier before the class name. Although seale

Defining local Variables Assign only one time (read-only) Local variables: Val a:int = 1 val b = 1//' Int ' type is inferred val c:int//type required when No. initializer is provided c = 1//definite assignment Variable variable var x = 5//' Int ' type is inferred x + = 1 Properties and Fields Defining propertiesYou can have properties in a class of Kotlin. These can be declared as mutable, using the Val keyword var keyword or read-only. p

Kotlin Object expressions and object declarations Kotlin uses object expressions and object declarations to implement an object that creates a class that makes minor changes to a class, and does not need to declare a new subclass. an object expression An object that implements an anonymous inner class through an object expression is used in the parameters of the method: Window.addmouselistener (Object:mous

Public Fun readbloghtml (blog:string): observable { return Observable.just (blog ), assembleurl (blog)} , readhtml (URL)}}I was a little confused ...And in fact Flatmap is not needed, because Kotlin read the source of the Web page is a word ... Public Fun readhtml (url:string): observable { return Observable.create { - subscriber.onnext (URL). ReadText ()); Subscriber.oncompleted () }}It's better

Antonio LeivaTime: Sep 12, 2016Original link: http://antonioleiva.com/recyclerview-diffutil-kotlin/As you know, the "Support Library 24" includes a new, applicable, and convenient class: Diffutil, which allows you to get rid of the boredom and error of cell changes and updates.If you don't know it yet, you can read Nicola Despotoski's good article about it. This article explains how easy it is to handle it.In fact, the Java language introduced many te

I wrote it once. Kotlin parsing JSON But, it's really bad, it's just erased, and now it's all sorted out again. By the way, record a little problem that has been going on for a long time today.1. Let's start with the simplest.A JSON string: ===== is called jsonstring.{ "code": "$", "MSG": "Success", "debugmsg": "", "result":{ "Data": "1231414"} }Well, how to parse it???You can use a function toFun get_key_string (key:string,jsonstring:string):

visible to the file in which they are located, and cannot be used in files other than the definition of this class protected can be visible to members themselves and their successors (for example, classes and its subclasses) internal to the entire module where the public The least restrictive modifier. This is the default modifier delegate Property A property has some of the same behavior, and using lazy or observable can be fun to reuse. Instead of declaring those same code over and over again

Packages A source file typically starts with a definition package Package Com.doctorq.packages Fun Main (args:array Note that this place is not directly related to the directory where the package name and source files are located, and the compiled file will install the defined package name to generate the appropriate directory Default imported Package kotlin.* kotlin.annotation.* kotlin.collections.* kotlin.comparisons.* (since 1.1) kotlin.io.* k

NULL security An important feature of the Kotlin system is its commitment to eliminate null references. Avoid any NPE (nullpointerexception) exceptions. Defining a variable that is allowed to be empty in Kotlin is not allowed to be defined in an empty way. var a:string = "ABC"//Cannot be an empty var b:string? = "ABC"//Can be empty b.length//may error //second one more than the first one '? ' Null valu

Kotlin Condition Control an IF expression An If statement contains a Boolean expression and one or more statements. Traditional usage var max = a if (a We can also assign the result of an IF expression to a variable. Val max = if (a > B) { print ("Choose a") a } else { print ("Choose B") b } This also means that I don't need to have a ternary operator like Java, because we can use it to make it simple: Val C = if (condition) a el

Experience: Anko + Kotlin and ankotlin ● Dependency: compile 'org. jetbrains. anko: 0.10.0' ● Interface: Import android. view. viewimport org. jetbrains. anko. * import org. jetbrains. anko. sdk25.coroutines. onClickclass MainActivityUI: AnkoComponent ● Activity： import android.os.Bundleimport android.support.v7.app.AppCompatActivityimport org.jetbrains.anko.setContentViewclass MainActivity : AppCompatActivity() { override fun onCreate(savedInstan