|NO.Z.00034|——————————|BigDataEnd|——|Hadoop&Scala.V01|——|Scala.v01|继承|继承概念|

一、继承

### --- 继承的概念
~~~     Scala中继承类的方式和Java一样，也是使用extends关键字：

class Employee extends Person{
    
    var salary=1000
}

~~~     # 和Java一样，可在定义中给出子类需要而父类没有的字段和方法，或者重写父类的方法。

//Person类
class Person(name:String,age:Int)
//Student继承Person类
class Student(name:String,age:Int,var studentNo:String) extends Person(name,age) object Demo{
    def main(args: Array[String]): Unit = {
        val student=new Student("john",18,"1024")
}
}

~~~     # 上面继承部分的代码等效于下面的Java代码

//Person类
class Person{
    private String name;
    private int age;
    public Person(String name,int age){
        this.name=name;
        this.age=age;
    }
}

//Student继承Person类
class Student extends Person{
    private String studentNo;
    public Student(string name,int age,String studentNo){
        super(name,age);
        this.sutdentNo=studentNo;
    }
}

### --- 编程代码

package yanqi.cn.part05

class Person(name: String, age: Int){
  println("这是父类Person！")
}

class Student(name: String, age: Int, var stuNo: String) extends Person(name, age){
  println("这是子类Student！")
}

object ExtendsDemo {
  def main(args: Array[String]): Unit = {
    val student = new Student("jacky", 30, "1001")
//    student.stuNo="1002"
//    println(student.stuNo)
  }
}

### --- 编译打印

D:\JAVA\jdk1.8.0_231\bin\java.exe "-javaagent:D:\IntelliJIDEA\IntelliJ IDEA 2019.3.3\lib\idea_rt.jar=56444:D:\IntelliJIDEA\IntelliJ IDEA 2019.3.3\bin" -Dfile.encoding=UTF-8 -classpath D:\JAVA\jdk1.8.0_231\jre\lib\charsets.jar;D:\JAVA\jdk1.8.0_231\jre\lib\deploy.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\access-bridge-64.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\cldrdata.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\dnsns.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\jaccess.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\jfxrt.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\localedata.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\nashorn.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\sunec.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\sunjce_provider.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\sunmscapi.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\sunpkcs11.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\zipfs.jar;D:\JAVA\jdk1.8.0_231\jre\lib\javaws.jar;D:\JAVA\jdk1.8.0_231\jre\lib\jce.jar;D:\JAVA\jdk1.8.0_231\jre\lib\jfr.jar;D:\JAVA\jdk1.8.0_231\jre\lib\jfxswt.jar;D:\JAVA\jdk1.8.0_231\jre\lib\jsse.jar;D:\JAVA\jdk1.8.0_231\jre\lib\management-agent.jar;D:\JAVA\jdk1.8.0_231\jre\lib\plugin.jar;D:\JAVA\jdk1.8.0_231\jre\lib\resources.jar;D:\JAVA\jdk1.8.0_231\jre\lib\rt.jar;E:\NO.Z.10000——javaproject\NO.Z.00002.Hadoop\ScalaPro\out\production\ScalaPro;D:\JAVA\scala-2.12.2\lib\scala-library.jar;D:\JAVA\scala-2.12.2\lib\scala-reflect.jar yanqi.cn.part05.ExtendsDemo
这是父类Person！
这是子类Student！

Process finished with exit code 0

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Walter Savage Landor:strove with none,for none was worth my strife.Nature I loved and, next to Nature, Art:I warm'd both hands before the fire of life.It sinks, and I am ready to depart

                                                                                                                                                   ——W.S.Landor

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