JAVA-构造方法注意事项

package com.itheima02;

public class Student {
    private String name;
    private int age;
    //构造方法
//    public Student(){
//        System.out.println("无参构造方法");
//    }
    public Student(){}
    public Student(String name){
        this.name=name;
    }
    public Student(int age){
        this.age=age;
    }
    public Student(String name,int age){
        this.name=name;
        this.age=age;
    }
    public void show(){
        System.out.println(name+","+age);

    }

}

代码2

package com.itheima02;

public class StudentDemo {
    public static void main(String[] args) {
        Student s1=new Student();
        s1.show();


        //    public Student(String name){}
        Student s2=new Student("林青霞");
        s2.show();

        //    public Student(int age){
        //        this.age=age;
        //    }

        Student s3=new Student(30);
        s3.show();

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

        Student s4 =new Student("林青霞",30);
        s4.show();
    }
}

执行结果

null,0
林青霞,0
null,30
林青霞,30

Process finished with exit code 0