class Person{

  String name;

  int age;

  char gender;

  public Person (String name){

     this.name = name;

  }

   public Person (String name , int age){

     this.name = name;

     this.age = age;

  }

  public Person (String name , int age ,char gender){

     this.name = name;

     this.age = age;

     this.gender = gender;

  }  

  public void introduce(){

    System.out.println("我是"+name+"     今年"+age+"岁     性别： "+gender);

  }

}

class Person{

  String name;

  int age;

  char gender;

  public Person (String name){

     this.name = name;

  }

   public Person (String name , int age){

     this(name);//调用只有一个参数的构造函数（必须是此构造函数里的第一行）

     this.age = age;

  }

  public Person (String name , int age ,char gender){

     this(name,age);//调用有两个参数的构造函数（必须是此构造函数里的第一行）
     this.gender = gender; 
  }
 public void introduce(){ 
    System.out.println("我是"+name+" 今年"+age+"岁 性别： "+gender); 
 } 
}