如何检索用户在Java中输入到arraylist中的所有记录

Question

I am trying to retrieve every record that an arraylist contains. I have a class called ContactList which is the super class of another class called BusinessContacts. My first task is to print only the first name and last name of a contact. The second task is to print details of a contact that's related to its id number. The ContactList class has all the instance variables and the set/get methods and the toString() method. The BusinessContact class consists of only two instance variables that need to be appended to the ContactList class. How is can this be worked out? The code is below:

The ContactList class:

package newcontactapp;

public abstract class ContactList {

    private int iD;
    private String firstName;
    private String lastName;
    private String adDress;
    private String phoneNumber;
    private String emailAddress;

    // six-argument constructor
    public ContactList(int id, String first, String last, String address, String phone, String email) {
        iD = id;
        firstName = first;
        lastName = last;
        adDress = address;
        phoneNumber = phone;
        emailAddress = email;
    }

    public ContactList(){

    }

    public void displayMessage()
    {
        System.out.println("Welcome to the Contact Application!");
        System.out.println();
    }

    public void displayMessageType(String type)
    {
        System.out.println("This is a " + type);
        System.out.println();
    }

    public int getiD() {
        return iD;
    }

    public void setiD(int id) {
        iD = id;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String first) {
        firstName = first;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String last) {
        lastName = last;
    }

    public String getAdDress() {
        return adDress;
    }

    public void setAdDress(String address) {
        adDress = address;
    }

    public String getPhoneNumber() {
        return phoneNumber;
    }

    public void setPhoneNumber(String phone) {
        phoneNumber = phone;
    }

    public String getEmailAddress() {
        return emailAddress;
    }

    public void setEmailAddress(String email) {
        emailAddress = email;
    }


   public String toString(){


       return getiD() + "   " + getFirstName() + "     " + getLastName() + "     " + getAdDress() + "     " + getPhoneNumber() + "     " + getEmailAddress() + "\n" ;
   }
}

The BusinessContacts class:

package newcontactapp;


public class BusinessContacts extends ContactList {


    private String jobTitle;
    private String orGanization;

    // 
    public BusinessContacts(int id, String first, String last, String address, String phone, String email, String job, String organization){

        super();
        jobTitle = job;
        orGanization = organization;
    }

    public BusinessContacts(){

    }

    public String getJobTitle() {
        return jobTitle;
    }

    public void setJobTitle(String job) {
        jobTitle = job;
    }

    public String getOrGanization() {
        return orGanization;
    }

    public void setOrGanization(String organization) {
        orGanization = organization;
    }

    //@Override
    public String toString(){

        return super.toString()+ " " + getJobTitle()+ " " + getOrGanization() + "\n";
    }
}

Here is my main method class:

package newcontactapp;

import java.util.ArrayList;

//import java.util.Iterator;
import java.util.Scanner;

public class NewContactAppTest {

    //ArrayList<ContactList> fullList = new ArrayList<>();
    ArrayList<ContactList> bContacts = new ArrayList<>();
    ArrayList<ContactList> pContacts = new ArrayList<>();

    public static void main(String [] args)
    {

        ContactList myContactList = new ContactList() {};

        myContactList.displayMessage();

        new NewContactAppTest().go();
    }

    public void go()
    {
        ContactList myContactList = new ContactList() {};

        System.out.println("Menu for inputting a Business Contact or Personal Contact");
        System.out.println();

        Scanner input = new Scanner(System.in);

        System.out.println("Please enter a numeric choice below: ");
        System.out.println();
        System.out.println("1. Add a Business Contact");
        System.out.println("2. Add a Personal Contact");
        System.out.println("3. Display Contacts");
        System.out.println("4. Quit");
        System.out.println();

        String choice = input.nextLine();

        if(choice.contains("1")){
          String type1 = "Business Contact";
          myContactList.displayMessageType(type1);
          businessInputs();  
        }
        else if(choice.contains("2")){
            String type2 = "Personal Contact";
            myContactList.displayMessageType(type2);
            personalInputs();
        }
        else if(choice.contains("3")) {
            displayContacts();
            displayRecord();
        }
        else if(choice.contains("4")){
            endOfProgram();
        }
    }

    public void businessInputs()
    {
        BusinessContacts myBcontacts = new BusinessContacts();
        //ContactList myContactList = new ContactList() {};
        //ContactList nameContacts = new ContactList() {};

        bContacts.clear();
        int id = 0;
        myBcontacts.setiD(id);

        Scanner in = new Scanner(System.in);

            while(true){
                id = id + 1;
                myBcontacts.setiD(id);
                //myContactList.setiD(id);


                System.out.println("Enter first name ");
                String firstName = in.nextLine();
                //nameContacts.setFirstName(firstName);
                //myContactList.setFirstName(firstName);
                myBcontacts.setFirstName(firstName);


                System.out.println("Enter last name: ");
                String lastName = in.nextLine();
                //nameContacts.setLastName(lastName);
                //myContactList.setLastName(lastName);
                myBcontacts.setLastName(lastName);

                System.out.println("Enter address: ");
                String address = in.nextLine();
                //myContactList.setAdDress(address);
                myBcontacts.setAdDress(address);


                System.out.println("Enter phone number: ");
                String phoneNumber = in.nextLine();
                //myContactList.setPhoneNumber(phoneNumber);
                myBcontacts.setPhoneNumber(phoneNumber);


                System.out.println("Enter email address: ");
                String emailAddress = in.nextLine();
                //myContactList.setEmailAddress(emailAddress);
                myBcontacts.setEmailAddress(emailAddress);


                System.out.println("Enter job title: ");
                String jobTitle = in.nextLine();
                myBcontacts.setJobTitle(jobTitle);



                System.out.println("Enter organization: ");
                String organization = in.nextLine();
                myBcontacts.setOrGanization(organization);


                //bContacts.add(myContactList);
                bContacts.add(myBcontacts);

                //names.add(nameContacts);

                 //System.out.println("as entered:\n" + bContacts);

                System.out.println();
                System.out.println("Enter another contact?");

                Scanner input = new Scanner(System.in);
                String choice = input.nextLine();

                if(choice.equalsIgnoreCase("Y")) {
                     continue;
                 }

                else{
                 break;
                 }
            }
            //bContacts.add(myBcontacts);
go();
}

    public void personalInputs(){

        ContactList myContactList = new ContactList() {};
        PersonalContacts myPcontacts = new PersonalContacts();

        Scanner in = new Scanner(System.in);

        int id;
        id = 1;
        while(true){

            System.out.println("Enter first name; ");
                String firstName = in.nextLine();
                myContactList.setFirstName(firstName);
                myPcontacts.setFirstName(firstName);

                System.out.println("Enter last name: ");
                String lastName = in.nextLine();
                myContactList.setLastName(lastName);
                myPcontacts.setLastName(lastName);

                System.out.println("Enter address: ");
                String address = in.nextLine();
                myContactList.setAdDress(address);
                myPcontacts.setAdDress(address);

                System.out.println("Enter phone number: ");
                String phoneNumber = in.nextLine();
                myContactList.setPhoneNumber(phoneNumber);
                myPcontacts.setPhoneNumber(phoneNumber);

                System.out.println("Enter email address: ");
                String emailAddress = in.nextLine();
                myContactList.setEmailAddress(emailAddress);
                myPcontacts.setEmailAddress(emailAddress);

                System.out.println("Enter birth date");
                String dateOfBirth = in.nextLine();
                myPcontacts.setDateOfBirth(dateOfBirth);

                //pContacts.add(myContactList);
                pContacts.add(myPcontacts);

                id = id + 1;
                myContactList.setiD(id);

                System.out.println();
                System.out.println("Enter another contact?");

                Scanner input = new Scanner(System.in);
                String choice = input.nextLine();

                if (choice.equalsIgnoreCase("y")) {
                  continue;  
                 }
                 else{
                 break;
            }
        }
        go();
    }

    public void displayContacts(){


        System.out.println();
            for(ContactList name : bContacts){
            System.out.println(name.getiD() + "    " + name.getFirstName()+ "          " + name.getLastName());

        }
    }

    public void displayRecord(){

        System.out.println();
        System.out.println("Do you wish to see details of contact?");

        Scanner input = new Scanner(System.in);
        String choice = input.nextLine();

       if(choice.equalsIgnoreCase("Y")) {

       System.out.println();
       System.out.println("Enter the numeric key from the list to see more specific details of that record");
       System.out.println();
       Scanner key = new Scanner(System.in);


       System.out.println();
       ContactList record = new ContactList() {};       
       for(int i = 0; i < bContacts.size(); i++){
           record = bContacts.get(i);

               System.out.println(record.toString());
       }

       }
       else{
           go();
       }   


         /* else{
             System.out.println();
             System.out.println("This is a Personal Contact");
             System.out.println();
               for(int j = 0; j < pContacts.size(); j++){
                 ContactList pList = pContacts.get(j);         
                 pList = pContacts.get(j);
                 System.out.println(pList.toString());
                   }
               }*/

    }  

    public void endOfProgram(){

        System.out.println("Thank you! Have a great day!");
            Runtime.getRuntime().exit(0);
    }
}

Answer 1

If you're looking to get a value based on ID, try making a method that iterates over the contents of the ArrayList to find one that matches:

public ContactList getContactList(int id) {
    for (ContactList list : /*your ContactList List object*/) {
        if (list.getiD() == id) {
            return list;
        }
    }
    return null;
}

This will return null if none is found, or the first result in the list.