20.Java基础_对象的构造函数

 package pack1;

 public class Student {

     private String name;

     private int age;

     //构造方法

     //如果没有任何构造函数,系统会自动给一个无参构造函数

     public Student(){

         this.name="";

         this.age=0;

     }

     public Student(String name,int age){

         this.name=name;

         this.age=age;

     }

     public void show(){

         System.out.println(name+","+age);

     }

 }

package pack1;

//测试学生类

public class StudentDemo {

    public static void main(String[] args) {

        // 创建对象

        Student s1=new Student();

        Student s2=new Student("njt",22);

        s1.show(); //  ,0

        s2.show(); // njt,22

    }

}