好的，这是作业。我有arraylist分配来添加，显示，搜索和删除联系人。我的代码编译并且我拥有正确运行的所有正确方法，除了deleteMatch()方法。它编译并运行，但实际上并没有删除arrayList中的任何内容。我还需要回去做一次并验证输入并检查我知道的空值，但我可以做到这一点，我只是想先了解基础知识。任何有关此方法的帮助将不胜感激。
import java.util.ArrayList;
import java.util.Scanner;
public class ContactDatabase
{
private ArrayList<Contact> contacts; // ArrayList of contact
private static final int QUIT = 0; // Menu choices
private static final int ADD = 1;
private static final int LISTALL = 2;
private static final int SEARCH = 3;
private static final int DELETE = 4;
/**
* Default constructor - make a new ArrayList object with parameter type Contact,,
*/
ContactDatabase()
{ // Initialize the categories.// instantiate your ArrayList here
contacts = new ArrayList<Contact>();
}
/**
* inputContact inputs contact information from the keyboard.
* It then stores this new contact in the contacts ArrayList.
*/
public void inputContact()
{
Contact myContact;
Scanner input = new Scanner(System.in);
System.out.println("Please enter first name of new person");
String first = input.nextLine();
System.out.println("Please enter last name of new person");
String last = input.nextLine();
System.out.println("Please enter phone number xxxxxxxxxx");
String phone = input.nextLine();
System.out.println("Please enter e-mail");
String email = input.nextLine();
myContact = new Contact(first, last, phone, email);
contacts.add(myContact);
System.out.println("Details recorded:");
System.out.println(contacts);
}
/**
* displayAll iterates through the ArrayList of contacts and outputs each one
* to the screen.
*/
public void displayAll()
{
for (Contact entry : contacts)
System.out.println (entry);
}
/**
* displayMatch inputs a keyword from the user.
* It then iterates through the ArrayList of contacts and outputs each one
* to the screen if the contact information contains the keyword.
*/
public void displayMatch()
{
if(contacts.isEmpty())
{
System.out.println("Sorry, there is no contact information to search.");
}
else
{
Scanner input = new Scanner(System.in);
System.out.print("Please enter the search keyword for or 0 to quit: ");
String search = input.next().trim().toUpperCase();
if (search.equals("0") == false)
{
boolean found = false;
for(Contact a: contacts)
{
if((a.getFirst().toUpperCase().equals(search))||(a.getLast().toUpperCase().equals(search))||(a.getPhone().toUpperCase().equals(search))||(a.getEmail().toUpperCase().equals(search)))
{
System.out.println("that contact info is: ");
System.out.println("name: " + a.getFirst());
System.out.println("name: " + a.getLast());
System.out.println("phone number: " + a.getPhone());
System.out.println("email: " + a.getEmail());
found = true;
}
else
{
found = false;
System.out.println("Sorry, that contact can not be found!");
}
}
}
}
}
/**
* deleteMatch inputs a keyword from the user.
* It then iterates through the ArrayList of contacts and asks the user
* if the contact should be deleted, if the contact information contains the keyword.
*/
public void deleteMatch()
{
if(contacts.isEmpty())
{
System.out.println("Sorry, there is no contact information to search.");
}
else
{
Scanner input = new Scanner(System.in);
System.out.print("Please enter the search keyword for or 0 to quit: ");
String search = input.next().trim().toUpperCase();
if (search.equals("0") == false)
{
boolean found = false;
for(Contact a: contacts)
{
if((a.getFirst().toUpperCase().equals(search))||(a.getLast().toUpperCase().equals(search))||(a.getPhone().toUpperCase().equals(search))||(a.getEmail().toUpperCase().equals(search)))
{
System.out.println("that contact info is: ");
System.out.println("name: " + a.getFirst());
System.out.println("name: " + a.getLast());
System.out.println("phone number: " + a.getPhone());
System.out.println("email: " + a.getEmail());
found = true;
Scanner inp = new Scanner(System.in);
System.out.println("Are you sure you would like to remove this contact?");
String sure = inp.next().toUpperCase();
if (sure.equals("YES"))
{
contacts.remove(a);
System.out.println("Contact removed... ");
displayAll();
}
}
else
{
found = false;
System.out.println("Sorry, that contact can not be found!");
}
}
}
}
}
// run through the array and look for an item that matches e
// get keyword input from user to be used in search
// run through list and look for any Contact that has
// the keyword
// prompt user to make sure they want to delete the
// (next/current) Contact you found
// if yes, delete the Contact
// Main class
public static void main(String[] args)
{
ContactDatabase cdb = new ContactDatabase();
Scanner scan = new Scanner(System.in);
int choice = ADD;
// Main menu
while (choice != QUIT)
{
System.out.println();
System.out.println("Choose from the following:");
System.out.println("0) Quit");
System.out.println("1) Add new contact");
System.out.println("2) List all contacts");
System.out.println("3) Search contacts by keyword and display");
System.out.println("4) Search contacts by keyword and remove");
choice = scan.nextInt();
switch (choice)
{
case ADD: cdb.inputContact();
break;
case LISTALL: cdb.displayAll();
break;
case SEARCH: cdb.displayMatch();
break;
case DELETE: cdb.deleteMatch();
break;
}
}
}
class Contact
{
private String first, last, phone, email;
/**
* Constructors.
*/
public Contact()
{
}
public Contact(String first, String last, String phone, String email)
{
this.first = first;
this.last = last;
this.phone = phone;
this.email = email;
}
/*
* Accessor Methods
*/
public String getFirst()
{
return first;
}
public String getLast()
{
return last;
}
public String getPhone()
{
return phone;
}
public String getEmail()
{
return email;
}
/*
* Mutator Methods
*/
public void setFirst(String first)
{
this.first = first;
}
public void setLast(String last)
{
this.last = last;
}
public void setPhone(String phone)
{
this.phone = phone;
}
public void setEmail(String em)
{
this.email = em;
}
/*
* Return all fields concatenated into a string
*/
public String toString()
{
return last + ", " + first + ". " + phone + ", " + email;
}
public boolean equals(Object otherObject)
{
if (otherObject ==null)
{
return false;
}
else if (getClass() != otherObject.getClass())
{
return false;
}
else
{
Contact otherContact = (Contact)otherObject;
return (first.equals(otherContact.first) &&
last.equals(otherContact.last)&&
phone.equals(otherContact.phone)&&
email.equals(otherContact.email));
}
}
} // end inner class, Contact
} // end class, ContactDatabase
感谢大家的帮助。我终于开始工作了！这是最终的代码：
import java.util.ArrayList;
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* The ContactDatabase class stores each contact in an arraylist.
* Methods exist to add new contacts, search contacts, delete, and print contacts
* to the console.
*/
public class ContactDatabase
{
private ArrayList<Contact> contacts; // ArrayList of contact
private static final int QUIT = 0; // Menu choices
private static final int ADD = 1;
private static final int LISTALL = 2;
private static final int SEARCH = 3;
private static final int DELETE = 4;
/**
* Default constructor - make a new ArrayList object with parameter type Contact,,
*/
ContactDatabase()
{
contacts = new ArrayList<Contact>();
}
/**
* inputContact inputs contact information from the keyboard.
* It then stores this new contact in the contacts ArrayList.
*/
public void inputContact()
{
Contact myContact;
String first = "null";
String last = "null";
String phone = "000-0000000";
String email = "xxx@example.com";
Scanner input = new Scanner(System.in);
while (true)
{
System.out.println("Please enter first name of new person");
first = input.nextLine();
if (first == null)
{
System.out.println("Sorry, first name cannot be null!");
}
else
{
break;
}
}
while (true)
{
System.out.println("Please enter last name of new person");
last = input.nextLine();
if (first == null)
{
System.out.println("Sorry, last name cannot be null!");
}
else
{
break;
}
}
while (true)
{
System.out.println("Please enter phone number 540-555-1212");
String vphone = input.nextLine();
Pattern pattern = Pattern.compile("\\d{3}-\\d{3}-\\d{4}");
Matcher matcher = pattern.matcher(vphone);
if ((matcher.matches())|| vphone != null)
{
System.out.println("Thank you.");
phone = vphone;
break;
}
else
{
System.out.println("Sorry, that entry is incorrect or null");
}
}
while (true)
{
System.out.println("Please enter e-mail xyz@xyz.com");
String vemail = input.nextLine();
Pattern pattern = Pattern.compile(".+@.+\\.[a-z]+");
Matcher matcher = pattern.matcher(vemail);
if ((matcher.matches())||(vemail != null))
{
System.out.println("Thank you.");
email = vemail;
break;
}
else
{
System.out.println("Sorry, that entry is incorrect");
}
}
myContact = new Contact(first, last, phone, email);
contacts.add(myContact);
System.out.println("Details recorded:");
System.out.println(contacts);
}
/**
* displayAll iterates through the ArrayList of contacts and outputs each one
* to the screen.
*/
public void displayAll()
{
System.out.println("Current contact list entries:");
for (Contact entry : contacts)
System.out.println (entry);
}
/**
* displayMatch inputs a keyword from the user.
* It then iterates through the ArrayList of contacts and outputs each one
* to the screen if the contact information contains the keyword.
*/
public void displayMatch()
{
boolean found = false;
Scanner input = new Scanner(System.in);
System.out.print("Please enter the search keyword for or 0 to quit: ");
String search = input.next().trim().toUpperCase();
if (search.equals("0") == false)
{
for(Contact a: contacts)
{
if((a.getFirst().toUpperCase().equals(search))||(a.getLast().toUpperCase().equals(search))||(a.getPhone().toUpperCase().equals(search))||(a.getEmail().toUpperCase().equals(search)))
{
System.out.println("that contact info is: ");
System.out.print("name: " + a.getFirst());
System.out.println(" " + a.getLast());
System.out.println("phone number: " + a.getPhone());
System.out.println("email: " + a.getEmail());
found = true;
}
if(contacts.isEmpty())
{
System.out.println("Sorry, there is no contact information to search.");
}
}
}
if (found == false)
{
System.out.println("Sorry, no such contact");
}
}
/**
* deleteMatch inputs a keyword from the user.
* It then iterates through the ArrayList of contacts and asks the user
* if the contact should be deleted, if the contact information contains the keyword.
*/
public void deleteMatch()
{
for (int i=0; i< contacts.size(); i++)
{
displayMatch();
Scanner inp = new Scanner(System.in);
System.out.println("Are you sure you would like to remove this contact?");
String sure = inp.next().toUpperCase();
if (sure.equals("YES"))
{
contacts.remove(i);
System.out.println("Thank you. Contact removed.");
displayAll();
}
}
}
// Main class
public static void main(String[] args)
{
ContactDatabase cdb = new ContactDatabase();
Scanner scan = new Scanner(System.in);
int choice = ADD;
// Main menu
while (choice != QUIT)
{
System.out.println();
System.out.println("Choose from the following:");
System.out.println("0) Quit");
System.out.println("1) Add new contact");
System.out.println("2) List all contacts");
System.out.println("3) Search contacts by keyword and display");
System.out.println("4) Search contacts by keyword and remove");
choice = scan.nextInt();
switch (choice)
{
case ADD: cdb.inputContact();
break;
case LISTALL: cdb.displayAll();
break;
case SEARCH: cdb.displayMatch();
break;
case DELETE: cdb.deleteMatch();
break;
}
}
}
/**
* The inner class, Contact, stores the details for a single contact.
* There is no error checking on any of the input. Whatever string is
* passed in for a given attribute is accepted.
*/
class Contact
{
private String first, last, phone, email;
/**
* Constructors.
*/
public Contact()
{
}
public Contact(String first, String last, String phone, String email)
{
this.first = first;
this.last = last;
this.phone = phone;
this.email = email;
}
/*
* Accessor Methods
*/
public String getFirst()
{
return first;
}
public String getLast()
{
return last;
}
public String getPhone()
{
return phone;
}
public String getEmail()
{
return email;
}
/*
* Mutator Methods
*/
public void setFirst(String first)
{
this.first = first;
}
public void setLast(String last)
{
this.last = last;
}
public void setPhone(String phone)
{
this.phone = phone;
}
public void setEmail(String em)
{
this.email = em;
}
/*
* Return all fields concatenated into a string
*/
public String toString()
{
return last + ", " + first + ". " + phone + ", " + email;
}
public boolean equals(Object otherObject)
{
if (otherObject ==null)
{
return false;
}
else if (getClass() != otherObject.getClass())
{
return false;
}
else
{
Contact otherContact = (Contact)otherObject;
return (first.equals(otherContact.first) &&
last.equals(otherContact.last)&&
phone.equals(otherContact.phone)&&
email.equals(otherContact.email));
}
}
} // end inner class, Contact
} // end class, ContactDatabase
答案 0 :(得分：3)
如果你覆盖了equals方法，你不需要检查单个字段，你可以简单地创建一个新信息的新联系人，然后只需调用arrayList.remove（contact_ob）;如果它存在，它将删除
也用于比较你使用string.toUpper（）的字符串.equals（other_str）;相反你可以使用string.equalsIgnoreCase（otherString），无论如何都会比较
答案 1 :(得分：0)
您正在尝试删除（对象）不正确的内容。 根据索引或计数器删除对象......这肯定会解决您的问题。
在你尝试删除基于对象的对象
之间这将解决您现在的问题，但请考虑重写equals方法并删除对象
答案 2 :(得分：0)
您需要在此代码中更改一些内容。
1]与equalsIgnoreCase匹配。切勿将值转换为大写或小写，然后匹配它。它限制用户输入特定的案例。
2]输入时，您需要检查已输入的重复值。
3]您需要在搜索特定联系人后将其删除并将其删除。
4]始终制作一个Contact对象，然后将其用于匹配。