大家好我还在学习Java专门的数组我想要做的就是创建一个迷你数据库。我想检索一个姓名，电话号码和电子邮件地址，当我打电话给一个名字时，我希望这里显示的信息是我到目前为止所得到的：
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);
}
}
答案 0 :(得分：1)
您可以使用此方法，首先为Customer创建一个bean类，如下所示：
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
}
现在你可以像这样使用它：
// 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);
现在您无需为保存数据声明三个不同的lists
答案 1 :(得分：1)
如果你想要做的是能够根据他们的名字显示特定的客户信息，那么你可以通过循环nArray并比较价值来实现这一目的。
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));
}
你真的可能想要上课Customer，而不是有3个不同的ArrayList。
答案 2 :(得分：0)
您应该对接口进行编程并确保数据的安全性。 您应该封装哪些更改。您不希望传递引用，这可能会导致更改用户信息（这是不需要的）。这可能会导致数小时的调试。大多数领域的Getter和Setter方法都违背了OO设计的目的，描述here。不是说你做过或做过，而是作为参考所有正在阅读和感兴趣的人。
/*
* 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));
}
};
}