Class & Object : 101

Demonstrates,

1. [] : Parameterized Types
2. () : Argument List for Member Variables
3. Unit
4. class
5. object
6. and more...

package e11_Classes.a11_101

//** Member variables are given in the argument list...
//  ie (mArg1, mArg2)
//** Outermost curly braces {} also acts as Primary Constructor #PS:12
class ClassWithMemberVariable(mArg1: String, mArg2: Int) {
  //** Square bracket([]) is used to Parameterize types
  //** Equal to (=) Separates Method signature from Method Body
  //** String* : Star is appended to denote variable length argument
  //             list
  //** Seq     : Is an Abstraction for Collections that can be 
  //             iterated in a fixed order
  def demoFunction(arg1: String*): Seq[String] = {
    println("ClassWithMemberVariable : Members are -> ", mArg1, 
                                        ", ", mArg2)
    println("Method arguments are -> ", arg1)                                        
    arg1
  }
}

// **Argument List..ie () not needed in the Class definition
// if we do not have any member variables
class ClassWithoutMemberVariable {
  // **When a function do not return anything
  // its return type can be denoted by Unit 
  def demoFunction : Unit = {
    println("ClassWithoutMemberVariable")  
  }
  //** Curly braces {} used to enclose the body of the method
  //   can be omitted if the method has only single expression
  def sayHello = "Hello"
}

// ** object : An object will have only one instance and there
//             conforms to the Singleton pattern
object a15_ConsDemo {
  def main(args: Array[String]) {
    val obj1 = new ClassWithMemberVariable("val1", 101)
    obj1.demoFunction("val1", "val2", "val3")
    
    //** Note here the absence of Argument list
    //...round brackets ie..()
    val obj2 = new ClassWithoutMemberVariable
    obj2.demoFunction
  }
}

> run-main e11_Classes.a11_101.a15_ConsDemo
[info] Compiling 1 Scala source to /Users/raj/gitws/scalaexamples/target/scala-2.10/classes...
[info] Running e11_Classes.a11_101.a15_ConsDemo
(ClassWithMemberVariable : Members are -> ,val1,, ,101)
(Method arguments are -> ,WrappedArray(val1, val2, val3))
ClassWithoutMemberVariable
[success] Total time: 1 s, completed Apr 29, 2016 9:45:39 PM

Here WrappedArray wraps Java Array