scala基础17-多重继承/混入特质需重写抽象方法

class Human {  println("Human")}/* * 和java不同，trait可以继承普通的类 * trait不能实例化 */trait TTeacher extends Human {  println("TTeacher")  def teach}trait PianoPlayer extends Human {  println("PianoPlayer")  def playPiano = {    println("I am playing piano")  }}/* * 多重继承 * 构造顺序从左往右 * scala规则：不会重复构造，如下面的程序TTeacher、PianoPlayer不会重复构造Human */class PianoTeacher extends Human with TTeacher with PianoPlayer {  override def teach = {    println("I am training students")  }}object Test {  def main(args: Array[String]) {//    def t1 = new PianoTeacher//    t1.playPiano//    t1.teach        //创建对象时混入特质，要重写trait中的抽象方法    def t2 = new Human with TTeacher with PianoPlayer {      override def teach = {        println("t2: I am training studend")      }    }    t2.playPiano    t2.teach  }}