关于java:driver class做什么(数组)

driver class what to do (array)

我正在尝试使用对象数组列表创建一个驱动程序类，它需要我：

从用户那里读取书名
阅读用户的书 ISBN
从用户处读取库存数量的图书
程序应该继续从用户那里读取图书信息，直到用户在所有字段中的所有条目都为空白或为零。
程序会将有效的书籍对象存储到一个 ArrayList 中(只有有效的对象)
然后，您的程序将以与输入书籍相反的顺序打印用户输入的所有"有效"书籍的列表。
当用户输入信息时，程序应该提供反馈，例如报告已将项目添加到 ArrayList，或报告发现的任何错误。
具有无效条目的书籍未添加到 ArrayList，因此在打印 ArrayList 时不会打印它们

这是我目前的驱动程序代码：(我对此有点陌生)
编辑：给出的答案

这是我现在得到的

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51

import java.io.*;
import java.util.*;

public class Bookstore2{

public static void main(String arg[ ]) throws Exception{

Scanner sc = new Scanner(System.in);
int isbn=0;
int quantity = 0;
String title ="";
Book oneBook;
List<Book> bookList = new ArrayList<Book>(); //here

while(true){
System.out.print("Enter title:");
title = sc.nextLine( );
sc = new Scanner(System.in);
System.out.println();
System.out.print("Enter isbn:");
isbn = sc.nextInt( );
sc = new Scanner(System.in);
System.out.println();
System.out.print("Enter quantity:");
quantity = sc.nextInt( );
sc = new Scanner(System.in);
sc = new Scanner(System.in);
System.out.println();

// WRITE YOUR VALIDATION CODE HERE
// Change condition according to your requirements.
if(isbn !=0 && quantity != 0 && title != null && title !="")
{
oneBook = new Book(title, isbn, quantity);
bookList.add(oneBook); //create a list in main
System.out.println("Book added in the list.");
}
else
{
System.out.println("Book not added");
break;
}

}
for(int i = bookList.size()-1; i >= 0; i--){
System.out.println(bookList.get(i));
}
} //main method
} //class

现在避免了错误，但它似乎没有同时利用我的异常和书籍类

这是我的类和我的异常，它将与新的驱动程序类一起运行

-----类

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70

public class Book{
//instance variables
private String title ="";
private int isbn;
private int quantity;

public Book (String title, int isbn, int quantity)throws BookException{
//constructors

setTitle(title);
setIsbn(isbn);
setQuantity(quantity);

}
public String toString( ){ //toString Method

String s ="";
s = s +"Title:" + this.title +"\
ISBN:" + this.isbn + "\
Quantity:" + this.quantity +"\
";
return s;

}

public String getTitle( ){
return this.title;
}
public int getisbn( ){
return this.isbn;
}
public int getquantity( ){
return this.quantity;
}

//mutator methods
public void setTitle(String newtitle )throws BookException{
if(newtitle.length()<1){
BookException be = new BookException( );
be.setMessage("Title cannot be blank");
throw be;
}
else{
this.title=newtitle;
}
}

public void setIsbn(int newisbn)throws BookException{
if (isbn <= 1000 || isbn >= 10000) {
this.isbn = newisbn;
}
else{
BookException be = new BookException( );
be.setMessage("ISBN should be between 1000 and 10000.");
throw be;
}
}

public void setQuantity(int newquantity)throws BookException{
if(newquantity>=0){
this.quantity = newquantity;
}
else{
BookException be = new BookException( );
be.setMessage("Quantity can't be a negative number.");
throw be;
}
}

}

------异常类

1
2
3
4
5
6
7
8
9
10
11
12

public class BookException extends Exception {
//instance variable
private String message ="";

public void setMessage(String newMessage) {
this.message = newMessage;
}

public String getMessage() {
return this.message;
}
}

相关讨论

由于代码有很多混乱，这里有一个完整的任务解决方案：

书店.java:

public class Bookstore {
static final Scanner in = new Scanner(System.in);
static List<Book> books = new ArrayList<>();

public static void main(String arg[]) throws Exception {
while (true) {
// read book information
Book book = new Book();
System.out.print("Enter title:");
book.title = in.nextLine();
System.out.println();

System.out.print("Enter ISBN:");
book.isbn = readInt();
System.out.println();

System.out.print("Enter quantity:");
book.quantity = readInt();
System.out.println();

// exit condition:"blank book" entered
if (book.title.isEmpty() && book.isbn == 0 && book.quantity == 0) {
System.out.println("Goodbye!");
break;
}

//validate and add book
try {
validateBook(book);
books.add(book);
System.out.println("Book successfully added to the list.");
} catch (IllegalStateException ex) {
System.err.println("Book is not valid:" + ex.getMessage());
continue;
}

// print book list
for (int i = books.size() - 1; i >= 0; i--) {
System.out.println(books.get(i));
System.out.println();
}
}
}

static int readInt() {
while (true) {
String input = in.nextLine();
if(input.isEmpty()) {
return 0;
}
try {
return Integer.parseInt(input);
} catch (NumberFormatException ex) {
System.err.println("Expected a valid integer:" + input);
}
}
}

static void validateBook(Book book) {
if (book.title == null || book.title.isEmpty()) {
throw new IllegalStateException("Book title must not be blank.");
}
if (book.isbn < 1000 || book.isbn > 10000) {
throw new IllegalStateException("Book ISBN must be between 1000 and 10000.");
}
if (book.quantity < 0) {
throw new IllegalStateException("Book quantity must be positive.");
}
}
}

Book.java:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15

public class Book {
public String title;
public int isbn;
public int quantity;

@Override
public String toString() {
return String.join("\
",
"Title:" + title,
"ISBN:" + isbn,
"Quantity:" + quantity
);
}
}