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
    }
}