访问权限

实现多继承

1.先父后子 2.有多个父亲，按书写顺序从左到右执行

package level02

object Class19 {
  trait A {
    println("A")
  }
  trait B {
    println("B")
  }
  class Class1 extends A with B{
    println("Class1")
  }
  def main(args:Array[String]): Unit = {
    new Class1()
  }
}

package level02

object Class19 {
  trait A {
    println("A")
  }
  trait BB {
    println("BB")
  }
  trait B extends BB{
    println("B")
  }
  class Class1 extends B with A{
    println("Class1")
  }
  def main(args:Array[String]): Unit = {
    new Class1()
  }
}

package level02

object Class19 {
  trait A {
    println("A")
  }
  trait BB {
    println("BB")
  }
  trait B extends BB{
    println("B")
  }
  trait CC {
    println("CC")
  }
  trait C extends CC{
    println("C")
  }
  
  class Class1 extends B with A{
    println("Class1")
  }
  def main(args:Array[String]): Unit = {
    new Class1()
  }
}

在文件中写入日志

package level02

import java.io.FileWriter
object Class20 {
  trait FileLogger {
    println(2)

    val filename:String
    lazy val fileWriter = new FileWriter(filename,true)
    def writeLog(msg:String):Unit = {
      fileWriter.write(msg)
      fileWriter.close()
    }
  }
  class MyFileLogger extends FileLogger{
    println(1)
    val filename = "11-26.log"
  }
  def main(args:Array[String]):Unit = {
    val filelogger = new MyFileLogger()
    filelogger.writeLog("今天上午上scala课程")
  }
}

访问权限控制

公开的。不能写修饰符

package level02

object Person {
  def test(p:Person):Unit = {
    println(p.password)
  }
}
class Person() {
  var name:String = "xx";
  protected var birthday:String = "2000-10-10"
  private var password:String="123456"
  private[this] var money:Int=100
  def t():Unit = {
    println(money)
  }
}
class Son extends Person(){
  println(birthday)
}
def main(args:Array[String]):Unit = {
  val p1 = new Person()
  println(p1.name)
  new Son()
  Person.test(p1)
}