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
    }
}