2nd: Scala Object-oriented thorough mastery and spark source reading

Defining classes
Class Hiscala {
private var name = "Spark"
Def sayname () {println (name)}
def getname=name
}

Instantiating classes
scala> val scal = new Hiscala
Scal:hiscala = [email protected]

Methods to invoke a class
Scala> Scal.sayname ()
Spark

Scala> Scal.getname
res6:string = Spark

Class Hiscala {
var name = "Scala"
Def sayname () {println (name)}
def getname=name
}

Access to public getter,setter
Scala> println (Scal.name)
Scala

Scala> Scal.name
res9:string = Scala

Overriding the default getter and setter note that the _= is connected together
Class Person {
private var myName = "Flink"
def name = This.myname
def name_= (newname:string) {
Myname=newname
println ("Hi:" + myName)
}
}

Scala> Rocky.name
res10:string = Flink

scala> rocky.name= "Spark"
Hi:spark
rocky.name:String = Spark

Private[this] is represented as private class, object private, can only be used by the object of the class, cannot be used by methods of the current class
Class Person {
private var myName = "Flink"
def name = This.myname
def name_= (newname:string) {
Myname=newname
println ("Hi:" + myName)
}
Def talk (P:person) = {
println ("Hello" +p.name)
}
}

val p1 = new person
val P2 = new person
P2.name= "Spark"

Scala> P1.talk (p2)
Hello Spark

However, after the following modifications, name is not a member of the person, only the object access
Class Person {
Private[this] var name = "Flink"
Def talk (P:person) = {
println ("Hello" +p.name)
}
}

Private[package-name] ...
That is, all classes and objects in the Package-name package can access the members behind private.

constructor function
Class Person {
var name = "Flink"
var age = 18
def this (name:string) {
This ()
This.name=name
}
def this (name:string,age:int) {
This (name)
This.age=age
}
}

The default constructor, such as Class Sparkcontext (config:sparkconf), is put together with the name

Class Person {
println ("Big Data")//default constructor will execute all code blocks that are not placed in the method
var name = "Flink"
var age = 18
def this (name:string) {
This ()
This.name=name
}
def this (name:string,age:int) {
This (name)
This.age=age
}
}

Scala> val p = new Person ("Spark", 20)
Big Data
P:person = [email protected]

Object associated objects, must be in the same file

Class Person {
var name = "Flink"
var age = 18
def this (name:string) {
This ()
This.name=name
}
def this (name:string,age:int) {
This (name)
This.age=age
}
}

For storing constants and static methods
Object Person {
println ("Scala")//Call only once
var salary = 0.0
def getsalary = Salary
}

Scala> person.getsalary
Scala
res16:double = 0.0

Scala> person.getsalary
res17:double = 0.0

Abstract class
Interface trait

Homework: Analyze the two classes of Sparkcontext and rdd yourself

2nd: Scala Object-oriented thorough mastery and spark source reading