Scala sample class

//  Sample class 
// Scala in , The sample class is a special class , It is generally used to save data （ Be similar to Java Bean）, In concurrent programming and Spark、Flink It is often used in these frameworks 
//  Format 
// case class  Sample class name ([var/val]  Member variable name 1: type 1,  Member variables 2: type 2,  Member variable name 3: type 3){}
//
//  If you don't write , The default modifier of the variable is val, namely val Omission 
//  If you want to implement a member variable, the value can be modified , You need to add it manually var To modify variables 
object  Sample class  {
    

  case class Person(name: String = " Zhang San ", var age: Int = 10) {
    }

  def main(args: Array[String]): Unit = {
    
    val p = Person()
    println(s" Before the change :name = ${p.name}, age = ${p.age}")
    // p.name="" //  Report errors , The default modifier without is val, Do not modify the 
    p.age = 18
    println(s" After modification :name = ${p.name}, age = ${p.age}")
  }

}