Scala Basic part 1 - vaquarkhan/Apache-Kafka-poc-and-notes GitHub Wiki

val is not reassignable.
var is reassiganable (rarley used)

lazy val is lazyly update value example

     lazy val a={println("evaluated");5}
     evaluated
     a: Int = <lazy>
     
     a
     a: Int = <lazy>
     res1: Int = 5

lazy val will not evaluated until referenced
Any subsequent call to the val will return the same value when initially called upon
There is no such initially called upon
lazy val can be forgivingif an excetion happends

Valid OPCHAR : Unicode Character from \u0020-\u007F

http://unicode.org/charats/PDF/U000.pdf

If Else If

Example 1:

  val num =10;
  val reult ="";

  if(num<10){
    result ="less then 10";
   }else if(num >10){
    result ="greter then 10";
   }else{
    result ="is 10";
   }

Example 2:

  val num =10;
  val reult ="";

  if(num<10)  result ="less then 10";
  else if(num >10)  result ="greter then 10";
  else result ="is 10";

Example 3:

  val num =10;
  val reult =   if(num<10)  "less then 10";
  else if(num >10)  "greter then 10";
  else "is 10";

While

var a=100; var result ="";

while(a > 0){ result =result +a; if(a < 0) result =result +","; a=a-1; }

print(result)

    val result =( 1 to 100).reverse.mkString(",")
   println(result )

   println(( 100 to 1 by -1 ).reverse.mkString(","))

Do while

 var a=100
 var result=""
 do{
  result =result +a
  if(a > 1)   result = result +","
  a=a-1
    }while (a >0)
   println(result)

Note : var a = 0 then only execute at least once but while not execute once Not using in scala as we can achive same using function programming

For loop

 var result ="";
 for(a <- 1 to  100){
 result = result +a
 if( a < 1000 result=result +","
 }
 println(result)

val xs= List(1,2,3,4)
var result=List[Int]()  //since List is empty we need to add List[Int]() to make it Int List

result = result :+ (a + 1)
println(result)

or functional for loop

  val xs = List(1,2,3,4)
  val result =for ( a<- xs) yield( a + 1)
  println(result)

String Interpolation

   val a= 99
    print( s" {$a} test String interpolation")

   val a= 99
    print( s" $a test String interpolation")

Method

   def add(x:Int ,y:Int) :int = {
   //body of the method
    return (x+y)
    }


def <method start > (x:int< input param namr>,y:Int) : Int <mehod return type > =<suppose to return something>{
 
 //method body
  return (x+y)
}

     def add(x:Int ,y:Int) return (x+y)

Types returned from a method are inferred
Type inferencer will make the best judgment
If types are diffrent it will find a common ancestor

Unit :

val g = () q:Unit=()

Unit will get when nothing to get , as compare to java "Unit =Void "

Scala Basic part 1 - vaquarkhan/Apache-Kafka-poc-and-notes GitHub Wiki

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