java 语言的编译错误
compilation errors in java language
您好,我有库 class 未完成,我在库中遇到编译问题 class
import java.util.Scanner;
public class Library {
// Add the missing implementation to this class
public static void printOpeningHours(){
System.out.println("Libraries are open daily from 9am to 5pm.");
}
public void printAddress(){
System.out.println("10 Main St.");
System.out.println("228 Liberty St.");
}
public void borrowBook(){
Scanner sc= new Scanner(System.in);
String x=sc.nextLine();
if (x=firstLibrary){
System.out.println("You successfully borrowed The Lord of the Rings");
firstLibrary.remove("The Lord of the Ring");
}else if{
System.out.println("Sorry, this book is already borrowed.");
}else (x=secondLibrary){
System.out.println("Sorry, this book is not in our catalog.");
}
}
public static void printAvailableBooks(){
return firstLibrary;
return secondLibrary;
}
public void returnBook(){
firstLibrary.add("The Lord of the Ring");
}
public static void main(String[] args) {
// Create two libraries
Library firstLibrary = new Library("10 Main St.");
Library secondLibrary = new Library("228 Liberty St.");
// Add four books to the first library
firstLibrary.addBook(new Book("The Da Vinci Code"));
firstLibrary.addBook(new Book("Le Petit Prince"));
firstLibrary.addBook(new Book("A Tale of Two Cities"));
firstLibrary.addBook(new Book("The Lord of the Rings"));
// Print opening hours and the addresses
System.out.println("Library hours:");
printOpeningHours();
System.out.println();
System.out.println("Library addresses:");
firstLibrary.printAddress();
secondLibrary.printAddress();
System.out.println();
// Try to borrow The Lords of the Rings from both libraries
System.out.println("Borrowing The Lord of the Rings:");
firstLibrary.borrowBook("The Lord of the Rings");
firstLibrary.borrowBook("The Lord of the Rings");
secondLibrary.borrowBook("The Lord of the Rings");
System.out.println();
// Print the titles of all available books from both libraries
System.out.println("Books available in the first library:");
firstLibrary.printAvailableBooks();
System.out.println();
System.out.println("Books available in the second library:");
secondLibrary.printAvailableBooks();
System.out.println();
// Return The Lords of the Rings to the first library
System.out.println("Returning The Lord of the Rings:");
firstLibrary.returnBook("The Lord of the Rings");
System.out.println();
// Print the titles of available from the first library
System.out.println("Books available in the first library:");
firstLibrary.printAvailableBooks();
}
}
库 class 的输出应该是这样的:
Library hours:
Libraries are open daily from 9am to 5pm.
Library addresses:
10 Main St.
228 Liberty St.
Borrowing The Lord of the Rings:
You successfully borrowed The Lord of the Rings
Sorry, this book is already borrowed.
Sorry, this book is not in our catalog.
Books available in the first library:
The Da Vinci Code
Le Petit Prince
A Tale of Two Cities
Books available in the second library:
No book in catalog
Returning The Lord of the Rings:
You successfully returned The Lord of the Rings
Books available in the first library:
The Da Vinci Code
Le Petit Prince
A Tale of Two Cities
The Lord of the Rings
我在 borrowBook() 和 printAvailableBooks() 以及 returnBook() 中遇到编译错误...主要方法不能修改...
如何更正以下方法的代码:borrowBook() 和 printAvailableBooks() 以及 returnBook()?
非常感谢:)
在 borrowBook()
中,您有一个 if
,然后是一个 else
,然后是一个 else if
。 else
应该始终排在最后:
if (x=firstLibrary){
System.out.println("You successfully borrowed The Lord of the Rings");
firstLibrary.remove("The Lord of the Ring");
} else if (x=secondLibrary){
System.out.println("Sorry, this book is not in our catalog.");
} else {
System.out.println("Sorry, this book is already borrowed.");
}
firstLibrary
和 secondLibrary
在 Library
中不存在,但我猜你还没有添加它。
在 printAvailableBooks()
中,您有两个背靠背的 return
语句。第二个永远达不到。此外,如果您只是想打印它们,请使用
System.out.println()
.
returnBook()
也会失败,因为 firstLibrary
不存在(与 borrowBook()
.
相同的原因
此外,我不会让 Library 扩展 Book。只需从逻辑上考虑它,而不要将其与编程联系起来。图书馆不是书。图书馆有书,所以也许你在图书馆里有一些变量来保存书籍的集合。
您好,我有库 class 未完成,我在库中遇到编译问题 class
import java.util.Scanner;
public class Library {
// Add the missing implementation to this class
public static void printOpeningHours(){
System.out.println("Libraries are open daily from 9am to 5pm.");
}
public void printAddress(){
System.out.println("10 Main St.");
System.out.println("228 Liberty St.");
}
public void borrowBook(){
Scanner sc= new Scanner(System.in);
String x=sc.nextLine();
if (x=firstLibrary){
System.out.println("You successfully borrowed The Lord of the Rings");
firstLibrary.remove("The Lord of the Ring");
}else if{
System.out.println("Sorry, this book is already borrowed.");
}else (x=secondLibrary){
System.out.println("Sorry, this book is not in our catalog.");
}
}
public static void printAvailableBooks(){
return firstLibrary;
return secondLibrary;
}
public void returnBook(){
firstLibrary.add("The Lord of the Ring");
}
public static void main(String[] args) {
// Create two libraries
Library firstLibrary = new Library("10 Main St.");
Library secondLibrary = new Library("228 Liberty St.");
// Add four books to the first library
firstLibrary.addBook(new Book("The Da Vinci Code"));
firstLibrary.addBook(new Book("Le Petit Prince"));
firstLibrary.addBook(new Book("A Tale of Two Cities"));
firstLibrary.addBook(new Book("The Lord of the Rings"));
// Print opening hours and the addresses
System.out.println("Library hours:");
printOpeningHours();
System.out.println();
System.out.println("Library addresses:");
firstLibrary.printAddress();
secondLibrary.printAddress();
System.out.println();
// Try to borrow The Lords of the Rings from both libraries
System.out.println("Borrowing The Lord of the Rings:");
firstLibrary.borrowBook("The Lord of the Rings");
firstLibrary.borrowBook("The Lord of the Rings");
secondLibrary.borrowBook("The Lord of the Rings");
System.out.println();
// Print the titles of all available books from both libraries
System.out.println("Books available in the first library:");
firstLibrary.printAvailableBooks();
System.out.println();
System.out.println("Books available in the second library:");
secondLibrary.printAvailableBooks();
System.out.println();
// Return The Lords of the Rings to the first library
System.out.println("Returning The Lord of the Rings:");
firstLibrary.returnBook("The Lord of the Rings");
System.out.println();
// Print the titles of available from the first library
System.out.println("Books available in the first library:");
firstLibrary.printAvailableBooks();
}
}
库 class 的输出应该是这样的:
Library hours:
Libraries are open daily from 9am to 5pm.
Library addresses:
10 Main St.
228 Liberty St.
Borrowing The Lord of the Rings:
You successfully borrowed The Lord of the Rings
Sorry, this book is already borrowed.
Sorry, this book is not in our catalog.
Books available in the first library:
The Da Vinci Code
Le Petit Prince
A Tale of Two Cities
Books available in the second library:
No book in catalog
Returning The Lord of the Rings:
You successfully returned The Lord of the Rings
Books available in the first library:
The Da Vinci Code
Le Petit Prince
A Tale of Two Cities
The Lord of the Rings
我在 borrowBook() 和 printAvailableBooks() 以及 returnBook() 中遇到编译错误...主要方法不能修改...
如何更正以下方法的代码:borrowBook() 和 printAvailableBooks() 以及 returnBook()?
非常感谢:)
在 borrowBook()
中,您有一个 if
,然后是一个 else
,然后是一个 else if
。 else
应该始终排在最后:
if (x=firstLibrary){
System.out.println("You successfully borrowed The Lord of the Rings");
firstLibrary.remove("The Lord of the Ring");
} else if (x=secondLibrary){
System.out.println("Sorry, this book is not in our catalog.");
} else {
System.out.println("Sorry, this book is already borrowed.");
}
firstLibrary
和 secondLibrary
在 Library
中不存在,但我猜你还没有添加它。
在 printAvailableBooks()
中,您有两个背靠背的 return
语句。第二个永远达不到。此外,如果您只是想打印它们,请使用
System.out.println()
.
returnBook()
也会失败,因为 firstLibrary
不存在(与 borrowBook()
.
此外,我不会让 Library 扩展 Book。只需从逻辑上考虑它,而不要将其与编程联系起来。图书馆不是书。图书馆有书,所以也许你在图书馆里有一些变量来保存书籍的集合。