java - 尝试测试Person类，不成功。

Question

好的，所以我应该创建 Person 类，其中包含用于保存人员姓名、地址和电话号码的字段，稍后将通过 Customer 类对其进行扩展。

    public class Person
{
   //Instance Variables
   private String name;
   private String street;
   private String cityStateZip;
   private String phone;

   //Constructors
   public Person()
   {
      String name = "";
      String street = "";
      String cityStateZip = "";
      String phone = "";
   }
   public Person(String name, String street, String cityStateZip,
                  String phone)
   {
      this.name = name;
      this.street = street;
      this.cityStateZip = cityStateZip;
      this.phone = phone;
   }
   public Person(Person person)
   {
      new Person();
   }

   //Mutators
   public void setName(String name)
   {
      this.name = name;
   }
   public void setStreet(String street)
   {
      this.street = street;
   }
   public void setCityStateZip(String cityStateZip)
   {
      this.cityStateZip = cityStateZip;
   }
   public void setPhone(String phone)
   {
      this.phone = phone;
   }

   //Accessors
   public String getName()
   {

   return name;
   }
   public String getStreet()
   {

   return street;
   }
   public String getCityStateZip()
   {

   return cityStateZip;
   }
   public String getPhone()
   {

   return phone;
   }
   public String toString()
   {

   return name + "/n" + street + "/n" + cityStateZip + "/n" + phone;
   }    
}

好吧，所以...我更改了一些代码，修复了我该死的私有(private)/公共(public)错误...我永远把+/-搞混了...这个文件现在可以编译了。我正在尝试创建一个类来测试它，但遇到了一些问题。这是我目前遇到的错误

----jGRASP 执行:javac -g TestPerson.java

TestPerson.java:23: error: cannot find symbol
      name = keyboard.nextLine;
                     ^
  symbol:   variable nextLine
  location: variable keyboard of type Scanner
TestPerson.java:27: error: cannot find symbol
      street = keyboard.nextLine;
                       ^
  symbol:   variable nextLine
  location: variable keyboard of type Scanner
TestPerson.java:31: error: cannot find symbol
      cityStateZip = keyboard.nextLine;
                             ^
  symbol:   variable nextLine
  location: variable keyboard of type Scanner
TestPerson.java:35: error: cannot find symbol
      phone = keyboard.nextLine;
                      ^
  symbol:   variable nextLine
  location: variable keyboard of type Scanner
TestPerson.java:38: error: non-static method getName() cannot be referenced from a static context
      getName()+ "\n" + getStreet() + "\n" + getCityStateZip() + "\n" 
      ^
TestPerson.java:38: error: non-static method getStreet() cannot be referenced from a static context
      getName()+ "\n" + getStreet() + "\n" + getCityStateZip() + "\n" 
                        ^
TestPerson.java:38: error: non-static method getCityStateZip() cannot be referenced from a static context
      getName()+ "\n" + getStreet() + "\n" + getCityStateZip() + "\n" 
                                             ^
TestPerson.java:39: error: non-static method getPhone() cannot be referenced from a static context
      + getPhone());
        ^
8 errors



 import java.util.Scanner;
import java.io.*;

public class TestPerson extends Person 
{


   public static void main(String[] args)
   {
      Scanner keyboard = new Scanner(System.in);

      String name;
      System.out.println("Enter your name: ");
      name = keyboard.nextLine;

      String street;
      System.out.println("Enter your street: ");
      street = keyboard.nextLine;

      String cityStateZip;
      System.out.println("Enter your city, state and zip code: ");
      cityStateZip = keyboard.nextLine;

      String phone;   
      System.out.println("Enter your phone number: ");
      phone = keyboard.nextLine;

      System.out.println("Tested person's information is as follows: " +
      getName()+ "\n" + getStreet() + "\n" + getCityStateZip() + "\n" 
      + getPhone());
      System.out.println(new Person());

      System.exit(0);
   }
}

Answer 1

您收到的确切错误是因为您采用了以前的公共(public)方法 (toString) 并将其设为私有(private)方法。

您的 Person 类的类型为 Object，因为 Java 中的所有类都继承自 Object。任何获得 Object 传递的人都希望它有一个可以使用的 toString 方法。如果 toString 是私有(private)的，则它们无法执行此操作，因此 Java 会提示。

顺便说一句，toString 中的代码看起来也是错误的。