Java 数组列表验证

Question

当用户将一个人添加到ArrayList时，我需要添加验证。输入名字和姓氏、地址、法定州缩写。等等。我该怎么办？

我想象了一个 IF 语句，但我不确定如何将其合并到 newFriend.setAddress(sc.nextLine()); 类型的行中。

import java.util.*;
import java.io.*;
import javax.swing.*;


public class testAddressBook {

    //Personal Friend Array
    public static PersonalFriend newFriend = new PersonalFriend(null, null, null, null, null, null, null, null, null, null,0,null);
    public static ArrayList<PersonalFriend> FriendList = new ArrayList<PersonalFriend>();

    //Business Associate Array
    public static BusinessAssociate newBusiness = new BusinessAssociate(null, null, null, null,null, null, null, null,null, null, null, null);
    public static ArrayList<BusinessAssociate> salaryList = new ArrayList<BusinessAssociate>();


    public static ArrayList<Person> addressBook = new ArrayList<Person>();
    private static Scanner sc = new Scanner(System.in);
    private static char choice;
    private static char type;


    public static void main(String[] args) throws IOException {

        boolean switcher = true;
        do {
            System.out.println("\n\tAddress Book Menu");
            System.out.println("\n\t\tEnter A to (A)dd Person ");
            System.out.println("\t\tEnter R to (R)emove Person");
            System.out.println("\t\tEnter M to (M)odify Entry");
            System.out.println("\t\tEnter S to (S)earch Address Book ");
            System.out.println("\t\tEnter L to (L)ist ALL (sorted) ");
            System.out.println("\t\tEnter D to (D)ownload to Disk ");
            System.out.println("\t\tEnter U to (U)pload from Disk ");
            System.out.println("\t\tEnter P to (P)rint Address Book ");
            System.out.println("\t\tEnter Q to Quit");
            System.out.print("\n\tPlease enter your choice: ");
            choice = sc.nextLine().toUpperCase().charAt(0);


            while ((choice != 'A') && (choice != 'R') && (choice != 'M')  && (choice != 'S') && (choice != 'L')&& (choice != 'D')&& (choice != 'U')&& (choice != 'P')&&(choice != 'Q')) {
                System.out.println("Invalid choice!  Please select (A)dd, (D)elete, (M)odify, (S)earch, (L)ist or (Q)uit: ");
                choice = sc.nextLine().toUpperCase().charAt(0);
            }


            switch (choice) {
            case 'A' :      
                if (choice == 'A') {
                    System.out.print("\nAdd a (F)riend or (B)usiness Associate? ");
                    type = sc.nextLine().toUpperCase().charAt(0);

                    while ((type != 'F') && (type != 'B')) {
                        System.out.print("Invalid choice!  Please select (F)riend or (B)usiness Associate: ");
                        type = sc.nextLine().toUpperCase().charAt(0);
                    }


                    if (type == 'F') {

                        addPersonFriend();

                    }

                    else if (type == 'B') {
                        addBusinessPerson();
                    }
                }


                break;

            case 'R' :
                deletePerson();
                break;

            case 'M' :
                modifyPerson();
                break;

            case 'S' :

                searchPerson();

                break;

            case 'L' :
                listPerson();
                break;

            case 'D' :
                downloadDisk();
                break;

            case 'U' :
                uploadDisk();
                break;

            case 'P' :
                printAddressBook();
                break;

            case 'Q' :
                switcher = false;

                break;


            }


        }
        while (switcher != false);
        System.out.println("Session Over");

    }


    private static void addPersonFriend() {
        System.out.println("\nFollow the prompts.");
        newFriend = new PersonalFriend(null, null, null, null, null, null, null, null, null, null,0,null);
        System.out.print("\nEnter First Name: ");
        newFriend.setfName(sc.nextLine());
        System.out.print("Enter Last Name: ");
        newFriend.setlName(sc.nextLine());
        System.out.print("Enter Address: ");
        newFriend.setAddress(sc.nextLine());
        System.out.print("Enter City: ");
        newFriend.setCity(sc.nextLine());
        System.out.print("Enter State: ");
        newFriend.setState(sc.nextLine());
        System.out.print("Enter Zip: ");
        newFriend.setZip(sc.nextLine());
        System.out.print("Enter Phone Number: ");
        newFriend.setPhone(sc.nextLine());
        System.out.print("Enter Cell Phone Number: ");
        newFriend.setCellphone(sc.nextLine());
        System.out.print("Enter Email Number: ");
        newFriend.setEmail(sc.nextLine());
        System.out.print("Enter Birthday: ");
        newFriend.setBirthday(sc.nextLine());
        System.out.print("Enter Age: ");
        newFriend.setAge(sc.nextInt());
        System.out.print("Enter Zodiac: ");
        newFriend.setZodiac(sc.nextLine());
        System.out.print(" ");
        newFriend.setZodiac(sc.nextLine());
        addressBook.add(newFriend);

        System.out.println("\nYou have successfully added a new person!");
    }

    private static void addBusinessPerson() {
        System.out.println("\nFollow the prompts.");
        newBusiness = new BusinessAssociate(null, null, null, null, null, null, null, null, null, null, null, null);
        System.out.print("\nEnter First Name: ");
        newBusiness.setfName(sc.nextLine());
        System.out.print("Enter Last Name: ");
        newBusiness.setlName(sc.nextLine());
        System.out.print("Enter Address: ");
        newBusiness.setAddress(sc.nextLine());
        System.out.print("Enter City: ");
        newBusiness.setCity(sc.nextLine());
        System.out.print("Enter State: ");
        newBusiness.setState(sc.nextLine());
        System.out.print("Enter Zip: ");
        newBusiness.setZip(sc.nextLine());
        System.out.print("Enter Phone Number: ");
        newBusiness.setPhone(sc.nextLine());
        System.out.print("Enter Cell Phone Number: ");
        newBusiness.setCellphone(sc.nextLine());
        System.out.print("Enter Email Number: ");
        newBusiness.setEmail(sc.nextLine());
        System.out.print("Enter Job Title: ");
        newBusiness.setJobtitle(sc.nextLine());
        System.out.print("Enter Fax Number: ");
        newBusiness.setFax(sc.nextLine());
        System.out.print("Enter Company Name: ");
        newBusiness.setCompany(sc.nextLine());      
        addressBook.add(newBusiness);

        System.out.println("\nYou have successfully added a new person!");
    }

    private static void deletePerson() {
        System.out.println("Enter first name of person: ");
        String deleteName = sc.nextLine();

        boolean foundMod = false;
        int index2 = 0;

        while (index2 < addressBook.size() && !foundMod) {
            if ( ((Person)addressBook.get(index2)).getfName().equalsIgnoreCase(deleteName)) {
                foundMod = true;
                addressBook.remove(index2);

                System.out.println("\nYou have successfully deleted this person.");
            }

            else {
                index2++;
            }

            if (foundMod)
            {}
            else
                System.out.println("Unknown");
        }

    }

    private static void modifyPerson() {

        newBusiness = new BusinessAssociate(null, null, null, null, null, null, null, null, null, null, null, null);
        newFriend = new PersonalFriend(null, null, null, null, null, null, null, null, null, null,0,null);


        System.out.print("Enter first name of person: ");
        sc.nextLine();



        if (newBusiness instanceof BusinessAssociate) {
            System.out.println("Change this business listing:  ");
            addBusinessPerson();
        }

        if (newFriend instanceof PersonalFriend) {
            System.out.println("This is a Personal Friend:  ");
            addPersonFriend();
        }


    }



    private static void searchPerson() {

        System.out.println("Enter first name of person: ");
        String findName = sc.nextLine();

        boolean found = false;
        int index = 0;

        while (index < addressBook.size() && !found) {
            if ( ((Person)addressBook.get(index)).getfName().equalsIgnoreCase(findName)) {
                found = true;
            }

            else {
                index++;
            }

            if (found)
                System.out.println("Found: " + addressBook.get(index));
            else{}

        }


    }

    private static void listPerson() {
        System.out.println("\nThere are " + addressBook.size() + " people in this address book.\n");
        Collections.sort(addressBook);


        for (int i = 0; i < addressBook.size(); i++) {
            System.out.println(addressBook.get(i));


        }
        System.out.println();



    }


    public static void downloadDisk() { 
        File file = new File("addressBookContents.dtd");


        // Create a file
        PrintWriter output = null;
        try {
            output = new PrintWriter(file);
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        // Write formatted output to the file
        output.println(addressBook);
        System.out.println("\nSaved to disk in the default folder for this program. \n");

        // Close the file
        output.close();

    }

    private static void uploadDisk() throws IOException {

        JFileChooser fileChooser = new JFileChooser();
        if (fileChooser.showOpenDialog(null)
                == JFileChooser.APPROVE_OPTION) {
            // Get the selected file
            java.io.File file = fileChooser.getSelectedFile();

            // Create a Scanner for the file
            Scanner input = new Scanner(file);

            // Read text from the file
            while (input.hasNext()) {
                System.out.println(input.nextLine());
            }

            // Close the file
            input.close();
        }
        else {
            System.out.println("No file selected");
        }


    }


    @SuppressWarnings("unchecked")
    private static void printAddressBook() {

        File file = new File("addressBookContents.txt");


        // Create a file
        PrintWriter output = null;
        try {
            output = new PrintWriter(file);
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        // Write formatted output to the file
        output.println(addressBook);
        System.out.println("\nPrinting Successful! \n");

        // Close the file
        output.close();

    }


}//ends class

Answer 1

确保对象有效的一个好方法是使其不可变，并在其构造函数中检查所有输入是否符合您的要求。

这里的复杂之处在于您在不同的步骤中获取大量信息。在调用带有大量参数的构造函数之前，您可以将每个变量存储在一个变量中，但这有点难以阅读。相反，请考虑 builder pattern