使用Java和面向对象创建联系人列表

Question

I am new to programming and object oriented design. This is my last requirement to finish my bachelors degree (not in programming). I am so confused with how to make object oriented work, and nothing I look at seems to help. The assignment is to create a contact list that uses inheritance, polymorphism,and collections. I need a contact list that is stores two types of contacts: business and personal. 1. Prompt to select which contact to add or display. 2. Prompt to allow user to enter the contact info. 3. Prompt that will display the output of a chosen contact back.

I have the following class and subclasses. I am stuck on how I am supposed to read in the inputs to the specific arraylists. I don't even know if the classes are built right either. Any help would be awesome, I just need to get through this, then I will gladly leave programing to those that know what they are doing.

This is what I have for my Parent Class:

package ooo1;

public abstract class Contact {

    private String contactId;
    private String firstName;
    private String lastName;
    private String address;
    private String phoneNumber;
    private String emailAddress;

    public Contact(String contactId,String firstName,String lastName, String address, String phoneNumber, String emailAddress)
    {
        this.contactId = contactId;
        this.firstName = firstName;
        this.lastName = lastName;
        this.address = address;
        this.phoneNumber = phoneNumber;
        this.emailAddress = emailAddress;
    }
    public void setContactId(String input){
        this.contactId = input;
    }
    public String getContactId(){
        return contactId;
    }

    public void setFirstName(String input){
        this.firstName = input;
    }
    public String getFirstName(){
        return firstName;
    }

    public void setLastName(String input){
        this.lastName = input;
    }
    public String getLastName(){
        return lastName;
    }

    public void setAddress(String input){
        this.address = input;
    }
    public String getAddress(){
        return address;
    }

    public void setPhoneNumber(String input){
        this.phoneNumber = input;
    }
    public String getPhoneNumber(){
        return phoneNumber;
    }

    public void setEmailAddress(String input){
        this.emailAddress = input;
    }
    public String getEmailAddress(){
        return emailAddress;
    }

    void displayContact(){
        System.out.println("Contact ID:" + contactId + " First Name:" + firstName + " Last Name:" + lastName);
        System.out.println("Address:" + address);
        System.out.println("Phone Number:" + phoneNumber);
        System.out.println("Email Address:" + emailAddress);
    }

}

This is one of my subclasses:

package ooo1;

public class PersonalContact extends Contact {

    private String dateofBirth;

    public PersonalContact(String contactId, String firstName, String lastName, String address, String phoneNumber, String emailAddress, String dateofBirth){

        super(contactId, firstName, lastName, address, phoneNumber, emailAddress);

        this.dateofBirth = dateofBirth;
    }
    public void setDateofBirth(String input){
        this.dateofBirth=input;
    }
    public String getDateofBirth(){
        return this.dateofBirth;
    }

}

This is my other subclass:

package ooo1;

public class BusinessContact extends Contact {

    private String jobTitle;
    private String organization;

    public BusinessContact(String contactId, String firstName, String lastName, String address, String phoneNumber, String emailAddress, String jobTitle, String organization){

        super(contactId, firstName, lastName, address, phoneNumber, emailAddress);

        this.jobTitle = jobTitle;
        this.organization = organization;
    }
    public void setJobTitle(String input){
        this.jobTitle = input;
    }
    public String getJobTitle(){
        return this.jobTitle;
    }

    public void setOrganization(String input){
        this.organization = input;
    }
    public String getOrganization(){
        return this.organization;
    }

}

This is what I have for Main which is so wrong at this point I believe:

package ooo1;

import java.util.ArrayList;
import java.util.Scanner;

public class ContactList {

    public static void main(String[] args) {

        ArrayList<PersonalContact> personalList = new ArrayList<PersonalContact>();

        Scanner input = new Scanner(System.in);
        System.out.println("Please enter ContactId : ");
        String contactId = input.nextLine();
        System.out.println("Please enter First Name : ");
        String firstName = input.nextLine();
        System.out.println("Please enter Last Name : ");
        String lastName = input.nextLine();
        System.out.println("Please enter Address : ");
        String address = input.nextLine();
        System.out.println("Please enter Phone Number : ");
        String phoneNumber = input.nextLine();
        System.out.println("Please enter Email Address : ");
        String emailAddress = input.nextLine();
        System.out.println("Please enter Birthday: ");
        String dateofBirth = input.nextLine(); 

    }

}

Answer 1

You have the pieces in place you just need to put them together. First, think about the List being used. It is supposed to hold both types of contacts, however its type argument is using the derived type PersonalContact . Instead use the base class Contact

 List<Contact> contacts = new ArrayList<Contact>();

Next it appears you start to gather the information about the contact from the end user via the console. Before doing this you may want to ask what type of contact is being entered, maybe give the option to enter 1 for a personal contact or 2 for a business contact. Then collect the information specific to the type of contact they chose.

Scanner input = new Scanner(System.in);
System.out.println("Please enter Specify the contact type (1 Personal, 2 Business) : ");
int contactType = input.nextInt();

//collect data common to both types
if(contactType == 1){
   //collect information specific to personal
} else if(contactType ==2){
   //collect information specific to business
}

Next you need to turn the data you collected into the actual objects, using a the constructors. This will need to be done conditionally and could actually be a part of the last section if done properly.

   Contact contact;
   if(contactType == 1){
       contact = new PersonalContact(/*arguments here*/);
   } else{
       contact = new BusinessContact(/*arguments here*/);
   }

Then finish up by adding the contact to your list:

   contacts.add(contact);

Answer 2

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package javaprac;

/**
 *
 * @author Arijit
 */
public class Contact {
    private String name;
    private int number;

    public Contact(int number,String name) {
        this.name = name;
        this.number = number;
    }

    public String getName() {
        return name;
    }

    public int getNumber() {
        return number;
    }

    public static Contact createContact(int number, String name){
        return new Contact(number,name);
    }



}

This is the Contact class, which is governed by a contact name and a contact number. Next we will design the MobilePhone class which will have a number(optional) and an arraylist of contacts.

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package javaprac;

import java.util.ArrayList;

/**
 *
 * @author Arijit
 */
class MobilePhone1 {
 public int mynumber;
 public ArrayList < Contact > contacts;

 public MobilePhone1(int mynumber) {
  this.mynumber = mynumber;
  this.contacts = new ArrayList < Contact > ();
 }

 public Boolean addContact(Contact contact) {
  if (findPosition(contact) >= 0) {
   System.out.println("Contact already is phone");
   return false;
  } else {
   contacts.add(contact);
  }

  return true;
 }

 public ArrayList < Contact > getContacts() {
  return contacts;
 }

 public void updateContact(Contact oldContact, Contact newContact) {
  if (findPosition(oldContact) >= 0) {
   contacts.set(findPosition(oldContact), newContact);
  } else {
   System.out.println("Contact does not exist");
  }
 }

 public void removeContact(Contact contact) {
  if (findPosition(contact) >= 0) {
   contacts.remove(findPosition(contact));
  } else {
   System.out.println("No contact");
  }
 }

 public int searchContact(Contact contact) {
  int position = findPosition(contact);
  if (contacts.contains(contact)) {
   System.out.println("Item found at position");
   return position;
  }
  System.out.println("Not found");
  return -1;
 }



 private int findPosition(Contact contact) {
  return this.contacts.indexOf(contact);

 }

 private int findPosition(String name) {
  for (int i = 0; i < contacts.size(); i++) {
   Contact contact = this.contacts.get(i);
   if (contact.getName().equals(name)) {
    return i;
   }
  }
  return -1;
 }


}

public class MobilePhone {
 public static void main(String args[]) {
  Boolean quit = false;
  int choice = 0;
  java.util.Scanner sc = new java.util.Scanner(System.in);
  MobilePhone1 phone = new MobilePhone1(98312);

  //Contact newcontact = Contact.createContact(12345,"Arijt");

  while (!quit) {
   System.out.println("Enter your choice");
   choice = sc.nextInt();
   sc.nextLine();


   switch (choice) {
    case 0:
     System.out.println("Enter the number of Contacts");
     int count = sc.nextInt();
     for (int i = 0; i < count; i++) {
      System.out.println("Enter number");
      int phoneNumber = sc.nextInt();
      System.out.println("Enter Name");
      sc.nextLine();
      String name = sc.nextLine();
      Contact newcontact = Contact.createContact(phoneNumber, name);
      phone.addContact(newcontact);
     }
     break;

    case 1:
     int size = phone.getContacts().size();
     System.out.println(size);
     for (int i = size - 1; i >= 0; i--) {
      phone.removeContact(phone.getContacts().get(i));
     }
     System.out.println(phone.getContacts().isEmpty());
     break;

    case 2:

     for (int i = 0; i < phone.getContacts().size(); i++) {
      System.out.println(phone.searchContact(phone.getContacts().get(i)));
     }
     break;

    case 3:

     //Contact newcontact1 = Contact.createContact(12345,"Buzz");
     System.out.println("Enter the Contact name you want to update");
     String oldContactName = sc.nextLine();

     for (int j = 0; j < phone.getContacts().size(); j++) {
      if (phone.getContacts().get(j).getName().equals(oldContactName)) {
       System.out.println("Enter the new Contact name");
       String newName = sc.nextLine();
       System.out.println("Enter the new Contact number");
       int newNumber = sc.nextInt();
       phone.updateContact(phone.getContacts().get(j), Contact.createContact(newNumber, newName));
      } else {
       System.out.println("You are looking for the wrong contact");
      }

     }


     for (int i = 0; i < phone.getContacts().size(); i++) {
      System.out.println(phone.getContacts().get(i).getName() + "," + phone.getContacts().get(i).getNumber());
     }
     break;

    case 4:
     if(phone.getContacts().isEmpty()){
         System.out.println("Emtpty contact list");

     }
     else {
         System.out.println("Contact list");
     for (int i = 0; i < phone.getContacts().size(); i++) {
      System.out.println("Name: "+phone.getContacts().get(i).getName() + ",Phone Number: " + phone.getContacts().get(i).getNumber());
     }
     }
     break;

    case 6:
        System.out.println("Enter 0 for adding contact\n");
        System.out.println("Enter 1 for removing every contact\n");
        System.out.println("Enter 2 for searching contact\n");
        System.out.println("Enter 3 for updating contact\n");
        System.out.println("Enter 4 for viewing the contact list\n");
        System.out.println("Enter 6 for exiting\n");
        System.out.println("Enter 5 to see the instrusctions again\n");
        break;
    case 5:
     quit = true;
     break;



   }
  }
 }
}