Speichern von mehreren Eingängen in einem Array

Question

Hallo Leute, ich lerne immer noch Java-spezifische Arrays, was ich versuche, eine Art Mini-Datenbank zu erstellen. Ich möchte einen Namen, Telefonnummer und E-Mail-Adresse abzurufen, und wenn ich auf einen Namen nennen möchte ich, dass Informationen hier angezeigt werden soll, was ich bisher habe:

private static String [][] info; 
    private static String name; 
    private static ArrayList<String> nArray = new ArrayList<>(); 
    private static ArrayList<String> pArray = new ArrayList<>(); 
    private static ArrayList<String> eArray = new ArrayList<>(); 

public static void addCustomer() 
{ 
     Scanner new_customer = new Scanner(System.in); 

     System.out.print("Name: ");   
     name = new_customer.nextLine(); 
     nArray.add(name); 

     System.out.print("Phone Number: "); 
     String phone = new_customer.nextLine(); 
     pArray.add(phone); 


     System.out.print("E-Mail Address: "); 
     String email = new_customer.nextLine(); 
     eArray.add(email);       
}  
    public static void customerInfo() 
{ 
    int totalCustomers = nArray.size(); 
    System.out.print("Current Customers : "+totalCustomers+" Total\n"); 
    StringBuilder arrayOutput = new StringBuilder(); 
    for (String name : nArray) { 
      arrayOutput.append(name+"\n"); 
    } 
    String text = arrayOutput.toString(); 
    System.out.print(text); 
} 
} 

Answer 1

Wenn Sie eine bestimmte Kundeninfo basierend auf ihrem Namen anzeigen möchten, können Sie dies tun, indem Sie die nArray Schleife durchlaufen und die Werte vergleichen.

public static int getCustomerIndex(String name){ 
    for (int q = 0; q < nArray.size(); q++){ 
     if (name.equals(nArray.get(q))){ 
      return q; 
     } 
    } 
    return -1; 
} 

public static void displayCustomer(int index){ 
    System.out.println("Name: " + nArray.get(index)); 
    System.out.println("Phone #: " + pArray.get(index)); 
    System.out.println("Email: " + eArray.get(index)); 
} 

Bu wirklich werden Sie wahrscheinlich wollen Customer eine Klasse machen, anstatt 3 verschiedene ArrayList zu haben.

Answer 2

Sie diesen Ansatz verwenden können, erstellen Sie zuerst eine Bean-Klasse für Customer wie unten:

public class Customer { 
    private String name; 
    private String phone; 
    private String email; 

    public Customer(String name, String phone, String email) { 
     this.name = name; 
     this.phone = phone; 
     this.email = email; 
    } 
    // getters and setters 
} 

Und dann jetzt können Sie es wie folgt verwenden:

// declare list for customers 
List<Customer> customers = new ArrayList<>(); 

// get the information from the user input 
.... 

// create Customer 
Customer customer = new Customer(name, phone, email); 

// add the Customer to the list 
customers.add(customer); 

jetzt haben Sie keine Notwendigkeit, drei verschiedenezu erklärenzum Speichern von Daten

Answer 3

Sie sollten auf Schnittstellen programmieren und die Sicherheit Ihrer Daten gewährleisten. Sie sollten die Änderungen einkapseln. Sie möchten nicht, dass Referenzen weitergegeben werden, was dazu führen kann, dass Benutzerinformationen geändert werden (dies ist unerwünscht). Dies kann zu Debugging-Stunden führen. Getter und Setter-Methoden für eine Mehrheit Ihrer Felder besiegt den Zweck von OO-Design, Beschreibung here. Nicht sagen, dass du es getan oder getan hast, sondern nur als Referenz für alle, die lesen und interessiert sind.

/* 
* 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 stackexchange; 

import stackexchange.user.*; 

import java.util.Set; 
import java.util.Map; 
import java.util.Scanner; 
import java.util.TreeSet; 
import java.util.TreeMap; 

/** 
* 
* @author Tony 
*/ 
public class StackExchange { 
    private static Set<Customer> dataset; 
    private static Map<String, Customer> emailQuery = null; 
    /** 
    * @param args the command line arguments 
    */ 
    @SuppressWarnings("empty-statement") 
    public static void main(String[] args) { 
     Scanner istream = new Scanner(System.in); 
     String in; 

     dataset = new TreeSet<>(Customer.comparator); 

     while (fillDatabase()); 

     printAll(); 

     while (true){ 
      System.out.print("Find User (y/n): "); 
      in = istream.nextLine(); 

      // If enter null break 
      if ("n".equals(in.toLowerCase())) 
       break; 

      System.out.print("Enter user Email: "); 
      in = istream.nextLine(); 
      printData(findByEmail(in)); 
     } 

    } 

    /** 
    * 
    * @return 
    */ 
    private static boolean fillDatabase(){ 
     Customer customer = new Customer(); 
     UserInfo userInfo; 
     String add; 
     String first; 
     String last; 
     String phone; 
     String email; 

     Scanner new_customer = new Scanner(System.in); 

     System.out.print("add user (y/n): ");   
     add = new_customer.nextLine(); 

     if ("y".equals(add.toLowerCase())){ 
      System.out.print("First Name: ");   
      first = new_customer.nextLine(); 

      System.out.print("Last Name: ");   
      last = new_customer.nextLine(); 

      System.out.print("Phone Number: "); 
      phone = new_customer.nextLine(); 


      System.out.print("E-Mail Address: "); 
      email = new_customer.nextLine(); 

      userInfo = new UserInfo(first, last, email, phone); 
      customer.setUserInfo(userInfo); 
      if (dataset.add(customer) == false){ 
       System.out.println("Customer : <" + first + " " + last + "> : already exists!"); 
      } 
      return (true); 
     } 
     return (false); 
    } 

    /** 
    * Get customer by id 
    * @param _id [in] customer 
    * @return 
    */ 
    private static Customer findByEmail(String _email){ 
     if (emailQuery == null){ 
      UserInfo userInfo; 
      emailQuery = new TreeMap<>(); 

      for (Customer c : dataset){ 
       userInfo = c.getUserInfo(); 
       emailQuery.put(userInfo.email, c); 
      } 
     } 

     return (emailQuery.get(_email)); 
    } 

    /** 
    * Print all data 
    */ 
    private static void printAll(){ 
     UserInfo userInfo; 

     for (Customer c : dataset){ 
      printData(c); 
     } 
    } 

    /** 
    * Print data 
    * @param _c [in] customer 
    */ 
    private static void printData(Customer _c){ 
     if (_c != null){ 
      UserInfo userInfo = _c.getUserInfo(); 
      System.out.println("+==================================================+"); 
      System.out.println("Name: " + userInfo.firstName + " " + userInfo.lastName); 
      System.out.println("Email: " + userInfo.email); 
      System.out.println("Phone#: " + userInfo.phoneNumber); 
      System.out.println("+==================================================+"); 
     }else{ 
      System.out.println("Error : customer cannot be null!"); 
     } 
    } 
} 


/* 
* 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 stackexchange.user; 

/** 
* Basic user information 
* @author Tony 
*/ 
public class UserInfo { 
    public final String firstName; 
    public final String lastName; 
    public final String email; 
    public final String phoneNumber; 

    public UserInfo(String _strFirstName, String _strLastName, String _strEmail, 
       String _strPhoneNumber){ 
     firstName = _strFirstName; 
     lastName = _strLastName; 
     email  = _strEmail; 
     phoneNumber = _strPhoneNumber; 
    } 

} 



/* 
* 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 stackexchange.user; 

/** 
* 
* @author Tony 
*/ 
public interface User { 
    public static final int PRIVILEGE_ADMIN = 0x00000001; 
    public static final int PRIVILEGE_NORMAL = 0x00000002; 
    public static final int PRIVILEGE_GUEST = 0x00000004; 
    public static final int PRIVILEGE_UNKNOWN = 0x80000000; 

    /** 
    * Getter Methods 
    */ 

    /** 
    * User privileges 
    * @return 
    */ 
    int getPrivilege(); 

    /** 
    * Object id 
    * @return id associated with this object 
    */ 
    String getObjectId(); 

    /** 
    * User information (immutable) 
    * @return instance of UserInfo 
    */ 
    UserInfo getUserInfo(); 

    /** 
    * Setter Methods 
    */ 

    /** 
    * Set user information 
    * @param _userInfo 
    */ 
    void setUserInfo(UserInfo _userInfo); 

} 


/* 
* 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 stackexchange.user; 

import java.util.Comparator; 

/** 
* 
* @author Tony 
*/ 
public class Customer implements User{ 
     private final String objectId; 
     private final int privilegeValue; 
     private String firstName; 
     private String lastName; 
     private String phoneNumber; 
     private String email; 

    public Customer(){ 
     objectId = this.hashCode() + "";   // Create Unique Id for each object 
     privilegeValue = User.PRIVILEGE_NORMAL; // user privileges 
    } 

    @Override 
    public int getPrivilege() { 
     return (privilegeValue); 
    } 

    @Override 
    public String getObjectId() { 
     return (objectId); 
    } 

    @Override 
    public UserInfo getUserInfo() { 
     UserInfo userInfo = new UserInfo(firstName, lastName, email, phoneNumber); 
     return (userInfo); 
    } 

    @Override 
    public void setUserInfo(UserInfo _userInfo) { 
     if (_userInfo == null){ 
      System.out.println("Error : argument passed cannot be null!"); 
     }else{ 
      firstName = _userInfo.firstName; 
      lastName = _userInfo.lastName; 
      email  = _userInfo.email; 
      phoneNumber = _userInfo.phoneNumber; 
     } 
    } 

    /** 
    * Compare two users 
    * @param _anotherCustomer [in] user to compare with 
    * @return comparison result 
    */ 
    public int compareTo(Customer _anotherCustomer){ 
     return (this.objectId.compareTo(_anotherCustomer.getObjectId())); 
    } 

    /** 
    * Used for sorting information in ADT's 
    */ 
    public static final Comparator<Customer> comparator = new Comparator<Customer>(){ 
     @Override 
     public int compare(Customer _c1, Customer _c2){ 
      return (_c1.compareTo(_c2)); 
     } 
    }; 
}