1. 说明

    （1）obj.isInstanceOf[T]：判断obj是不是T类型
    （2）obj.asInstanceOf[T]：将obj强转成T类型, 无法转换会报错
    （3）classOf获取对象的类名

    1. 案例实操 ```scala class Person { }

    object Person { def main(args: Array[String]): Unit = { val person = new Person

    1. //判断对象是否为某个类型的实例
    2. val bool: Boolean = person.isInstanceOf[Person]
    4. if (bool) {
    5.   //将对象转换为某个类型的实例
    6.   val p1: Person = person.asInstanceOf[Person]
    7.   println(p1)
    8. }
    10. //获取类的信息
    11. val pClass: Class[Person] = classOf[Person]
    12. println(pClass)

    } }

    2. ```scala
    3. object HelloWorld {
    4.   def main(args: Array[String]): Unit = {
    6.     // 1. 类型的检测和转换
    7.     val student: Student17 = new Student17("alice", 18)
    8.     student.study()   // student study
    9.     student.sayHi()   // hi from student alice
    10.     println("=================")
    11.     val person: Person17 = new Student17("bob", 20)
    12.     person.sayHi()    // hi from student bob
    13.     println("=================")
    15.     // 类型判断, 下面都是true
    16.     println("student is Student17: " + student.isInstanceOf[Student17])
    17.     println("student is Person17: " + student.isInstanceOf[Person17])
    18.     println("person is Person17: " + person.isInstanceOf[Person17])
    19.     println("person is Student: " + person.isInstanceOf[Student17])
    21.     val person2: Person17 = new Person17("cary", 35)
    22.     println("person2 is Student17: " + person2.isInstanceOf[Student17]) // false
    24.     // 类型转换
    25.     if (person.isInstanceOf[Student17]){
    26.       val newStudent = person.asInstanceOf[Student17]
    27.       newStudent.study()  // student study
    28.     }
    30.     println(classOf[Student17]) //class com.jdxia.chapter01.Student17
    31.   }
    32. }
    35. class Person17(val name: String, val age: Int){
    36.   def sayHi(): Unit = {
    37.     println("hi from person " + name)
    38.   }
    39. }
    41. class Student17(name: String, age: Int) extends Person17(name, age){
    42.   override def sayHi(): Unit = {
    43.     println("hi from student " + name)
    44.   }
    45.   def study(): Unit = {
    46.     println("student study")
    47.   }
    48. }