正确使用 "extends" 在命令行参数中显示继承

Question

用户应该按顺序在命令行中输入姓名、姓氏和年龄，然后它会显示在 JoptionPlane 中。然后它再次显示在年龄增加 1 的参数前面的博士。但是我的 Public Earthling 方法有问题，我不断收到错误

            "constructor Person in class Person cannot be applied to given types;
   public Earthling(String name1, String fn1, int age1){
                                                       ^
required: String,int
found: no arguments
reason: actual and formal argument lists differ in length
1 error

预期输出（对话框）：

Bill Johnson is 58 years old.
Dr. Bill Johnson is 59 years old.

这是我的代码：

import javax.swing.JOptionPane;

public class Inheritance {

 /**
  * main method which begins the program
  * 
  * @param args is the people and age inputed
  */
  public static void main(String[] args){
    if (args.length <= 1) {
      System.out.println("Please enter a viable argument");
      System.exit(1); // ends the program
    } 

    Integer age = Integer.parseInt(args[2]);

    // Creates a person object
    Earthling familyname1 = new Earthling(args[0],args[1], age);

    //put here first so it displays without the Dr.
    String firstOutput = familyname1.toString();

    //calls the phd and birthday methods
    familyname1.phd();
    familyname1.birthday();

    String secondOutput = familyname1.toString();

    JOptionPane.showMessageDialog(null, firstOutput);
    JOptionPane.showMessageDialog(null, secondOutput);
  }
}

/* Stores the first name and age for a person */
class Person {
  protected String name;
  protected Integer age;

  /**
   * The Constructer, used for creating objects and initializing data
   * 
   * @param n1 is the Persons first name
   * @param a1 is the Persons age
   * 
   */
   public Person(String n1, int a1){
      name = n1;
      age = a1;
   }

   /* adds Dr. to the name */  
   public void phd() {
     name = "Dr. " + name;
   }

   /* adds 1 to the age */
   public void birthday() {
     age = age + 1;
   }

   /**
    * displays the data in each objects data field
    * 
    * @return The Persons name, family name and age
    */
   public String toString(){
     String output = name + " is " + age + " years old.";
     return output;
   }
 }

class Earthling extends Person {      
  protected String familyName;

  //Problem Here!
  public Earthling(String name1,String fn1, int age1){
    name = name1;
    familyName = fn1;
    age = age1;   
  }

  public String toString() {
    String output = name + familyName + " is " + age + " years old.";
    return output;
  }
}

Answer 1

您需要在 Earthling 的构造函数中首先调用 super(name1, age1)。

有关 Java 中 super 关键字的解释以及调用超类的构造函数，请参阅 http://docs.oracle.com/javase/tutorial/java/IandI/super.html。

正确使用 "extends" 在命令行参数中显示继承

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