The class declared by the scala object keyword directly calls methods and associated objects

object Student {
    
  def test(): Unit = {
    
    println("test")
  }
}

object T5 {
    
  def main(args: Array[String]): Unit = {
    
    Student.test()
  }
}

   Static syntax is not object-oriented , therefore scala There is no static syntax in , In order to and java compatible , therefore scala Provide singleton objects to simulate static operations . Use Object Keyword declared class , Such as Student , can Directly access methods through class names , Such as Student.test().Student , Will produce 2 A class file , One is The current class Class files , The other is The current class $ Class files

   Class name $ Class in class file of The constructor is privatized , Cannot build objects directly , Inside the class Static code block You can return objects , And this object has only one , be called Singleton object , You can access the methods through this object

  Student.test() The singleton object is actually used Student$.MODULE$, namely Companion ： Object The declared class is accompanied by the singleton object generated by the class

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