[Java知识库]Scala-day01-伴生对象与helloworld

面向对象编程，但是静态变量school确是由类名调用的

初始scala

package chapter01

/*
  object:关键字，声明一个单例对象（伴生对象）
 */
object HelloWorld {
  /*
    main方法，从外部可以直接调用执行的方法
    def 方法名称(参数名称:参数类型):方法返回值类型={方法体}
   */
  def main(args: Array[String]): Unit = {
    println("hello world")
    System.out.println("hello world")
  }
}

?java：

public class Student {

    private String name;
    private Integer age;
    private static String school = "atguigu";

    public Student(String name,Integer age){
        this.name = name;
        this.age = age;
    }

    public void printInfo(){
        System.out.println(this.name + " " + this.age + " " + Student.school);
    }

    public static void main(String[] args) {
        Student alice = new Student("alice", 20);
        Student bob = new Student("bob", 23);
        alice.printInfo();
        bob.printInfo();
    }

}

引入伴生对象，与同名的class相伴相生，去除掉java中的static，school属性由student对象调用

class Student就相当于构造函数，def 自定义printInfo函数结构参照上面的结构介绍

main函数定义在object Student里面

scala：

package chapter01

class Student(name:String,age:Int) {

  def printInfo():Unit={
    println(name + " " + age + " " + Student.school);
  }

}

//引入伴生对象
object Student{
  val school:String = "atguigu"

  def main(args: Array[String]): Unit = {
    val alice = new Student("alice",20)
    val bob = new Student("bob",20)
    alice.printInfo()
    bob.printInfo()
  }
}