在学习上出了点问题

[aa14963944]

主类:

System.out.println("请输入书名：");
String bookname = sc.next();

System.out.println("请输入作者：");
String author = sc.next();

System.out.println("请输入出版社：");
String publisher = sc.next();

System.out.println("请输入单价：");
double price = sc.nextDouble();

System.out.println("请输入数量：");
int Num = sc.nextInt();

Book book=new Book(bookname, author, publisher, Num, price);
Book.In++;
System.out.println("增加的图书信息：");
Book.information();//
工具类 Book:
public static void information(){
Book B=bookList.get(In);
System.out.println("*****************给力图书**********************");
System.out.println("\t 书名: "+B.getBookname());
System.out.println("\t 作者: "+B.getAuthor());
System.out.println("\t 出版社: "+B.getPublisher());
System.out.println("\t 单价: "+B.getPrice());
System.out.println("\t 数量: "+B.getNum());
System.out.println("*****************给力图书**********************");
}
Book.information 输不出来 是什么问题？

[aa14963944]

Book类 import java.util.ArrayList; import java.util.Scanner; public class Book { private static String bookname; private static String author; private static String publisher; private static int Num=0; private static double price=0; private int p; public static ArrayList<Book> bookList= new ArrayList<Book>(); public static int In=0; public int getP() { return p; } public String getBookname() { return bookname; } public String getPublisher() { return publisher; } public int getNum() { return Num; } public double getPrice() { return price; } public String getAuthor() { return author; } public Book(String bookname,String author,String publisher,int Num,double price){ this.bookname=bookname; this.author=author; this.publisher=publisher; this.Num=Num; this.price=price; } public static void information(){ Book B=bookList.get(In); System.out.println("*****************给力图书**********************"); System.out.println("\t 书名: "+B.getBookname()); System.out.println("\t 作者: "+B.getAuthor()); System.out.println("\t 出版社: "+B.getPublisher()); System.out.println("\t 单价: "+B.getPrice()); System.out.println("\t 数量: "+B.getNum()); System.out.println("*****************给力图书**********************"); } public void setBookname(String bookname) { this.bookname = bookname; } public void setPublisher(String publisher) { this.publisher = publisher; } public void setNum(int num) { Num = num; } public void setPrice(double price) { this.price = price; } public void setAuthor(String author) { this.author = author; } public void setP(int p) { this.p = p; } public static void setBookList(ArrayList<Book> bookList) { Book.bookList = bookList; } public static ArrayList<Book> getBookList() { return bookList; } public void addBook(Book book){ bookList.add(book); } } 主类 System.out.println("****请选择您需要的操作****"); System.out.println("**** 1.图书添加 ****"); System.out.println("**** 2.图书删除 ****"); System.out.println("**** 3.图书修改 ****"); System.out.println("**** 4.图书记录****"); System.out.println("**** 5.返回上级菜单 ****"); System.out.println("**** 6.退出系统 ****"); int in=sc.nextInt(); switch(in){ case 1: do{ System.out.println("请输入书名："); String bookname = sc.next(); System.out.println("请输入作者："); String author = sc.next(); System.out.println("请输入出版社："); String publisher = sc.next(); System.out.println("请输入单价："); double price = sc.nextDouble(); System.out.println("请输入数量："); int Num = sc.nextInt(); Book book=new Book(bookname, author, publisher, Num, price); Book.In++; System.out.println("增加的图书信息："); Book.information(); Book.information()显示不出来

[Stluny]

然而 问题是什么

[绿树苍天]

主程序里面没看到你把book加到bookList里面

[家里敷泥呀]

Book B=bookList.get(In); // 这句话不报角标越界？

[尼古拉斯-全蛋]

booklist在哪赋值的，还有你那个In哪来的，建议把代码贴全一点

[aa14963944]

6楼 我把你的加进去了 报错

[纵一苇也]

艾玛，我都看不懂你的程序，怎么没有注释啊，格式又乱。

[HerveyHall]

应该是因为木有把Book对象添加到BookList中

 
            //...
  	      Book book=new Book(bookname, author, publisher, Num, price);
              BookList.getBookList().addBook(book);//加上这句
        	Book.In++;
        	System.out.println("增加的图书信息：");
        	Book.information();
            //...

[javaee3]

手动改了下你的代码，感觉有点乱····，我也是个新手····· 你的最后输出：Book.information();//Book貌似要改成小写book，0-0有可能改后还是不对···· 我写下了你的这个： import java.util.ArrayList; import java.util.List; import java.util.Scanner; public class Book { private String bookname; private String author; private String publisher; private int Num=0; private double price=0; private int p; public String getBookname() { return bookname; } public void setBookname(String bookname) { this.bookname = bookname; } public String getAuthor() { return author; } public void setAuthor(String author) { this.author = author; } public String getPublisher() { return publisher; } public void setPublisher(String publisher) { this.publisher = publisher; } public int getNum() { return Num; } public void setNum(int num) { Num = num; } public double getPrice() { return price; } public void setPrice(double price) { this.price = price; } public int getP() { return p; } public void setP(int p) { this.p = p; } public void information(Book book)//输出在控制台的方法 { List<Book> bookList= new ArrayList<Book>(); bookList.add(book); for(int i =0;i<=bookList.size()-1;i++) { Book B = bookList.get(i); System.out.println("*****************给力图书**********************"); System.out.println("\t 书名: "+B.getBookname()); System.out.println("\t 作者: "+B.getAuthor()); System.out.println("\t 出版社: "+B.getPublisher()); System.out.println("\t 单价: "+B.getPrice()); System.out.println("\t 数量: "+B.getNum()); } } public static void main(String[] args) { System.out.println("****请选择您需要的操作****"); System.out.println("**** 1.图书添加 ****"); System.out.println("**** 2.图书删除 ****"); System.out.println("**** 3.图书修改 ****"); System.out.println("**** 4.图书记录****"); System.out.println("**** 5.返回上级菜单 ****"); System.out.println("**** 6.退出系统 ****"); Scanner sc = new Scanner(System.in); System.out.print("请输入你要的操作:"); int in=sc.nextInt(); switch(in) { case 1: do { Book book=new Book();//设置书的相关信息，书名，作者，出版社，单价，数量 System.out.println("请输入书名："); book.setBookname(sc.next()); System.out.println("请输入作者："); book.setAuthor(sc.next()); System.out.println("请输入出版社："); book.setPublisher(sc.next()); System.out.println("请输入单价："); book.setPrice(sc.nextDouble()); System.out.println("请输入数量："); book.setP(sc.nextInt()); System.out.println("增加的图书信息："); book.information(book);//调用输出在控制台的方法 }while(true); } } }