public class Emp {
       private String name;
       private int age;
       public Emp(String name,int age){           //3
             this.name = name;                 //4
             this.age = age;                     //5
            System.out.println("emp1 is called");    //6
        }
        public Emp(String name){                //2
             this(name,20);                   //构造器代码的复用
            System.out.println("emp2 is called");     //7
        }
       public Emp(){
             this("张三",20);                //构造器代码的复用
            System.out.println("emp3 is called"); 
        }
        public static void main(String[] args){
               new Emp("zhang");               //1
        }
}
