我刚刚开始编程并遇到了一些小错误。我正在创建一个库对象，它保存对书对象和成员对象的引用，但是我无法从成员类访问方法并在库类中使用它们而没有在LibraryTester类中弹出错误。这就是我编码的内容
图书馆班级
package assignment;
import java.nio.channels.MembershipKey;
import java.util.ArrayList;
import java.util.Scanner;
import org.omg.Messaging.SyncScopeHelper;
public class Library {
// Declared an array list of type book
private ArrayList<Book> Books;
private MemberList members;;
public Library(ArrayList<Book> Books, Member member) {
this.Books = Books;
this.members=members;
};
public void displayBooks() {
System.out.println("\t\t\t-----The Current Books in the library are-----");
for (int i = 0; i < Books.size(); i++) {
System.out.println("\n" + "\t\t" + Books.get(i).getTitle() + "\t\t\t" + "\n\t\tAuthor: "
+ Books.get(i).getAuthor() + "\n\t\tThis Books ID is: " + Books.get(i).getBookID() + "\t\t\t\t\t\t"
+ "\n\t\tIs this book on loan? " + Books.get(i).getOnLoan() + "\t\t\t\t\t"
+ "\n\t\tThe number of times which this book has been loaned: " + Books.get(i).getNumOfLoans()
+ "\t\t");
}
}
// method to remove permanently a book object
public void removeBook() // the parameter that is passed through
// is the book id of the book that is to
// be removed
{
Scanner input = new Scanner(System.in);
int bookID = 0;
boolean successful = false;
try {
do {
System.out.println("Please enter the book ID of the book you wish to delete");
bookID = input.nextInt();
for (int i = 0; i < Books.size(); i++) {
if (bookID == Books.get(i).getBookID())
{
System.out.println("The Book " + Books.get(i).getTitle() + " was removed");
Books.remove(i);
successful = true;
break;
}
}
if (!successful) {
System.out.println("Book ID " + bookID + " does not exist");
}
} while (successful == false);
} catch (Exception e) {
System.out.println("ERROR: Invalid input" + "\nYou have been returned to the main menu");
}
}
public void editBook() {
boolean successful = false;
try {
do {
Scanner sc = new Scanner(System.in);
System.out.println("Please enter the book ID of the book who's details you wish to change");
int bookID = sc.nextInt();
sc.nextLine();
for (int i = 0; i < Books.size(); i++) {
if (Books.get(i).getBookID() == bookID) {
System.out.println("Please enter the new name of the book:");
String newTitle = sc.nextLine();
Books.get(i).setTitle(newTitle);
System.out.println("Please enter the name of the author of the book:");
String newAuthor = sc.nextLine();
Books.get(i).setAuthor(newAuthor);
System.out.println("Change of book details successful" + "\nNew book title: " + newTitle
+ "\nNew author: " + newAuthor);
successful = true;
}
}
if (!successful) {
System.out.println("This book does not exist ");
}
} while (successful == false);
} catch (Exception e) {
System.out.println("ERROR: Invalid input" + "\nYou have been returned to the main menu");
}
}
public void addBook() {
boolean successful = false;
int bookID = 0;
String title = "";
String author = "";
Scanner input = new Scanner(System.in);
do {
System.out.println("Please assign a 3 digit number for the books ID ");
bookID = input.nextInt();
input.nextLine();
if(bookID > 99 && bookID <1000){
for (int i = 0; i < Books.size(); i++) {
if(Books.get(i).getBookID()!= bookID){
successful = true;
} else {
System.out.println("This book ID already exists ");
}
}
} else { System.out.println("You must enter a number between 99 and 1000 ");
}
} while (successful == false);
do {
System.out.println("Please enter the name of book");
title = input.nextLine();
for (int i = 0; i < Books.size(); i++) {
if (Books.get(i).getTitle().equalsIgnoreCase(title)) {
System.out.println("ERROR: This book already exists");
successful = false;
} else {
successful = true;
}
}
} while (successful == false);
do {
System.out.println("Please enter the author of the book");
author = input.nextLine();
successful = true;
} while (successful == false);
Book Book = new Book(bookID, title, author, false, 0, 0);
Books.add(Book);
System.out.println(
"Book creation succcessful:" + "\nTitle: " + title + "\nAuthor: " + author + "\nBook ID:" + bookID);
}
public void loanBook() {
Scanner input = new Scanner(System.in);
boolean successful = false;
do {
System.out.println(
"\nPlease enter the book ID of the book that you wish to take out (Press 9 to exit to the main menu)");
int bookID = input.nextInt();
if (bookID == 9) {
successful = true;
break;
}
for (int i = 0; i < Books.size(); i++) {
if (Books.get(i).getBookID() == bookID) {
do {
System.out.println("\nHow long would you like to loan the book for (20 Days maximum):");
int durationOnLoan = input.nextInt();
if (durationOnLoan <= 20 && 1 <= durationOnLoan) {
Books.get(i).setDurationOnLoan(durationOnLoan);
successful = true;
} else {
System.out.println("The number of days you have entered is invalid");
}
} while (successful == false);
System.out.println("\nThe book " + Books.get(i).getTitle() + " is now on loan");
Books.get(i).setOnLoan(true);
Books.get(i).setNumOfLoan(Books.get(i).getNumOfLoans() + 1);
successful = true;
}
}
if (successful == false) {
System.out.println("This book does not exist ");
}
} while (successful == false);
}
public void returnBook() {
boolean successful = false;
Scanner input = new Scanner(System.in);
try {
do {
System.out.println(
"Please enter the book ID of the book you wish to return (Press 9 to exit to the main menu");
int bookID = input.nextInt();
input.nextLine();
if (bookID == 9) {
successful = true;
}
for (int i = 0; i < Books.size(); i++) {
if (Books.get(i).getBookID() == bookID) {
if (Books.get(i).getOnLoan() == true) {
System.out.println("How long did you loan the book for?");
int durationOnLoan = input.nextInt();
if (durationOnLoan > Books.get(i).getDurationOnLoan()) {
durationOnLoan -= Books.get(i).getDurationOnLoan();
if (durationOnLoan < 3) {
System.out.println("You are " + durationOnLoan
+ " day(s) late in returning the book" + "\nYou have been fined £3."
+ "\n The book " + Books.get(i).getTitle() + " is now returned");
successful = true;
} else {
System.out.println("You are " + durationOnLoan + " days late in returning the book"
+ "\nYou have been fined £6.");
System.out
.println("The book " + Books.get(i).getTitle() + " has now been returned");
successful = true;
}
} else {
Books.get(i).setOnLoan(false);
System.out.println("The book " + Books.get(i).getTitle() + " has now been returned");
successful = true;
}
} else if (Books.get(i).getOnLoan() == false) {
System.out.println("\nThis book was not on loan");
System.out.println("\nYou have been returned to the main menu");
successful = true;
}
} else if (successful == false) {
System.out.println("This book does not exist");
}
}
} while (successful == false);
} catch (Exception e) {
System.out.println("ERROR: Invalid input" + "\nYou have been returned to the main menu");
}
}
}
MemberList类
package assignment;
import java.util.Scanner;
import java.util.ArrayList;
public class MemberList {
private ArrayList<Member> Members;
public MemberList(ArrayList<Member> Members) {
this.Members = Members;
}
public void addNewMember() {
Scanner input = new Scanner(System.in);
boolean successful = false;
int memberID = 0;
String memberName = "";
int memberAge;
String address;
int contactNumber;
System.out.println("\t\tCreate new member");
do {
System.out.println("Please enter your full name:");
memberName = input.nextLine();
if (!input.hasNextInt()) {
successful =true;
} else {
input.next();
System.out.println("Your name cannot contain a number");
}
} while (successful == false);
do {
try{
input.nextLine();
System.out.println("please create your unique 2 digit member ID");
memberID = input.nextInt();
for (int i = 0; i < Members.size(); i++) {
if (Members.get(i).getMemberID() == memberID) {
System.out.println("This member ID is already in use");
successful =false;
}
if (memberID <= 9 || memberID > 99) {
System.out.println("PLease enter 2 digit ID (between 10 and 100) ");
}
if(Members.get(i).getMemberID() != memberID && memberID > 9 && memberID < 100) {
successful = true;
}
}
} catch(NumberFormatException e)
{
System.out.println("Invalid input");
}
} while (successful == false);
do{
System.out.println("Please enter your age: ");
memberAge = input.nextInt();
if(!input.hasNextInt())
{
System.out.println("Invalid input");
} else{successful =true;}
}while(successful == false);
do{
System.out.println("Please enter your adress");
address = input.nextLine();
successful =true;
}while(successful==false);
do {
System.out.println("please enter your contact number:");
contactNumber = input.nextInt();
if(!input.hasNextInt())
{
System.out.println("Invalid input");
} else{successful = true;}
}while(successful==false);
Member newMember = new Member(memberID,memberName,memberAge,0,0,address,contactNumber);
Members.add(newMember);
}
public void displayMembers()
{
System.out.println("\t\t\t-----The current members in the library are-----");
for (int i = 0; i < Members.size(); i++)
{
System.out.println("\n" + "\t\t" + Members.get(i).getMemberName() + "\t\t\t" + "\n\t\tMember ID: "
+ Members.get(i).getMemberID() + "\n\t\tAge: " + Members.get(i).getMemberAge() + "\t\t\t\t\t\t"
+ "\n\t\tAddress: " + Members.get(i).getAddress() + "\t\t\t\t\t"
+ "\n\t\tContact number: " + Members.get(i).getContactNumber()
+ "\t\t" + "\n\t\tNumber of books loaned: " + Members.get(i).getNumOfBooksLoaned()
+ "\t\t" + "\n\t\tNumber of Late Fees: " + Members.get(i).getPenalties());
}
}
}
LibraryTester类
package assignment;
import java.util.Scanner;
import java.util.ArrayList;
public class LibraryTester {
public static void main(String[] args) {
String title = "";
String author = "";
int bookID = 0;
ArrayList<Member> List = new ArrayList<Member>();
MemberList memberlist = new MemberList(List){};
Member John = new Member(10,"John McLaughlin", 44, 5, 0,"75 B Loughbeg Road Toomebridge",123456789);
List.add(John);
Member Cathy = new Member(11,"Cathy McLaughlin", 43, 7, 0,"75 B Loughbeg Road Toomebridge",123456789);
List.add(Cathy);
ArrayList<Book> list = new ArrayList<Book>();
Library library = new Library(list, );
Book HarryPotter = new Book(100, "Harry Potter and The Philosopher's Stone", "J.K Rowling", false, 5, 0);
list.add(HarryPotter);
Book theOriginOfSpecies = new Book(101, "The Origin Of Species", "Charles Darwin", false, 3, 0);
list.add(theOriginOfSpecies);
Book LOTR = new Book(102, "The Lord of The Rings: The Fellowship of The Ring", "J.R.R Tolkien", false,7,0);
list.add(LOTR);
Scanner input = new Scanner(System.in);
boolean B = true;
while (B == true) {
System.out.println(" \nMenu ");
System.out.println("Press 1 to add a book");
System.out.println("Press 2 to edit a books details");
System.out.println("Press 3 to delete a book");
System.out.println("Press 4 to take out a book on loan");
System.out.println("Press 5 to return a book");
System.out.println("Press 6 to see all the books in the library");
System.out.println("Press 7 to become a member");
System.out.println("Press 8 to see the members of the library");
System.out.println("Press 9 to exit the program");
switch (input.nextInt()) {
case 1:
library.addBook();
B = true;
break;
case 2:
library.displayBooks();
library.editBook();
B = true;
break;
case 3:
library.displayBooks();
library.removeBook();
B = true;
break;
case 4:
library.displayBooks();
library.loanBook();
B = true;
break;
case 5:
library.displayBooks();
library.returnBook();
break;
case 6:
library.displayBooks();
B = true;
break;
case 7:
memberlist.addNewMember();
break;
case 8:
memberlist.displayMembers();
B = true;
break;
case 9:
System.out.println("Exiting .....");
System.exit(1);
break;
default:
System.out.println("You have not entered a valid option");
break;
}
}
}
}
错误发生在代码
Library library = new Library(list , ) {
};
我不确定在逗号之后放什么，我已经尝试过所有内容，但似乎没有任何效果。有什么想法吗？
修改
已编辑的库类
package assignment;
import java.nio.channels.MembershipKey;
import java.util.ArrayList;
import java.util.Scanner;
import org.omg.Messaging.SyncScopeHelper;
public class Library {
// Declared an array list of type book
private ArrayList<Book> Books;
private ArrayList<Member> members;;
public Library(ArrayList<Book> Books, ArrayList<Member> member) {
this.Books = Books;
this.members=member;
};
已编辑的LibraryTester类
ArrayList<Member> List = new ArrayList<Member>();
MemberList memberList = new MemberList(List){};
ArrayList<Book> list = new ArrayList<Book>();
Library library = new Library(list, memberList ){};
错误说＆＃34;构造函数库（ArrayList，MemberList）未定义＆＃34;但是我改变了图书馆课程中的相关内容吗？
答案 0 :(得分：0)
你需要传递Book和一个成员的数组：
public Library(ArrayList<Book> Books, Member member)
答案 1 :(得分：0)
由于Library类具有构造函数
public Library(ArrayList<Book> Books, Member member){};
您不能像在LibraryTester类中那样创建对象。 你需要传递第二个参数，即Member类的对象。
答案 2 :(得分：0)
在这里你错过了一个成员：
Library library = new Library(list, );
尝试像这样添加它来创建Member的对象：
Member memberlist = new Member(10,"Joe Blogs", 44, 5, 0,"Bleaker Street",123456789);
Library library = new Library(list, memberlist);