Scala 特质（Trait）

 1 package chapter06
 2
 3 object Test13_Trait {
 4   def main(args: Array[String]): Unit = {
 5     val student: Student13 = new Student13
 6     student.sayHello()
 7     student.study()
 8     student.dating()
 9     student.play()
10   }
11 }
12
13 // 定义一个父类
14 class Person13 {
15   val name: String = "person"
16   var age: Int = 18
17   def sayHello(): Unit = {
18     println("hello from: " + name)
19   }
20   def increase(): Unit = {
21     println("person increase")
22   }
23 }
24
25 // 定义一个特质
26 trait Young {
27   // 声明抽象和非抽象属性
28   var age: Int
29   val name: String = "young"
30
31   // 声明抽象和非抽象的方法
32   def play(): Unit = {
33     println(s"young people $name is playing")
34   }
35
36   def dating(): Unit
37 }
38
39 class Student13 extends Person13 with Young {
40   // 重写冲突的属性
41   override val name: String = "student"
42
43   // 实现抽象方法
44   def dating(): Unit = println(s"student $name is dating")
45
46   def study(): Unit = println(s"student $name is studying")
47
48   // 重写父类方法
49   override def sayHello(): Unit = {
50     super.sayHello()
51     println(s"hello from: student $name")
52   }
53 }