借书还书java代码 java编写借书卡程序代码
java简单的借书系统
HashMap的常用方法
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map的存储和修改方式 map.put(key, value);
map是否包含某个元素map.containsKey(key);
map某个key的value值map.get(key);
参考代码
import java.util.HashMap;
public class BookTest {
static HashMapString, Integer map=new HashMapString, Integer();
static{//初始化图书信息
map.put("三国志", 8);
map.put("红楼梦", 0);
map.put("西游记", 15);
}
public static void main(String[] args) {//main方法
jieShu("水浒");
jieShu("三国志");
huanShu("三国志");
jieShu("红楼梦");
huanShu("红楼梦");
jieShu("红楼梦");
}
public static void jieShu(String name){//借书
if(!map.containsKey(name)){//查询图书馆是否有这本书
System.out.println("书籍："+name+"\t查无此书！");
return;
}
if(map.get(name)=0){//查询图书数量是否为0
System.out.println("书籍："+name+"\t已全部借出，请明日在来");
return;
}
map.put(name, map.get(name)-1);
System.out.println("书籍："+name+"\t借书成功。"+"\t库存："+map.get(name));
}
public static void huanShu(String name){//还书
if(!map.containsKey(name)){
System.out.println("查无此书");
}else{
map.put(name, map.get(name)+1);
System.out.println("书籍："+name+"\t还书成功。"+"\t库存："+map.get(name));
}
}
}
测试输出
书籍：水浒 查无此书！
书籍：三国志 借书成功。 库存：7
书籍：三国志 还书成功。 库存：8
书籍：红楼梦 已全部借出，请明日在来
书籍：红楼梦 还书成功。 库存：1
书籍：红楼梦 借书成功。 库存：0
借书还书数据库代码？
-- 图书借阅数据库设计
-- 记录每一本图书借出和还回的操作
-- 书的信息
DROP DATABASE IF EXISTS db_lib;
CREATE DATABASE db_lib;
use db_lib
SET @READER_MAX = 10;
SET @EVERY_DAY_FEE=0.1;
SELECT 10 INTO @temp;
-- 新建相关的表
CREATE TABLE books (
id INT PRIMARY KEY AUTO_INCREMENT,
name CHAR(255) NOT NULL,
price DECIMAL(8,2) DEFAULT 0
);
CREATE TABLE readers (
id INT PRIMARY KEY AUTO_INCREMENT,
name CHAR(255) NOT NULL,
borrowed INT DEFAULT 0
);
CREATE TABLE lib_books (
id INT PRIMARY KEY AUTO_INCREMENT,
info INT,
FOREIGN KEY(info) REFERENCES books(id),
stat CHAR(10) NOT NULL DEFAULT "在馆"
);
-- 记录借书和还书
CREATE TABLE lib_loan (
id INT AUTO_INCREMENT,
who INT,
which INT,
check_out DATETIME NOT NULL DEFAULT NOW(),
check_in DATETIME DEFAULT NULL,
renew BOOLEAN NOT NULL DEFAULT 0,
latest DATE NOT NULL,
fee DECIMAL(8,2) DEFAULT NULL,
PRIMARY KEY(id),
FOREIGN KEY(who) REFERENCES readers(id),
FOREIGN KEY(which) REFERENCES lib_books(id)
);
-- 给馆藏图书添加10本书
-- 存储过程
DELIMITER $$$
CREATE PROCEDURE add_books( IN n INT)
BEGIN
-- 需要有多行数据放入变量，需要用 游标 cursor
-- i 局部变量
DECLARE i INT DEFAULT 1;
-- @temp全局变量
SELECT COUNT(*) INTO @temp
FROM books;
WHILE i=n DO
INSERT INTO lib_books (info) VALUES ( FLOOR(RAND()*@temp)+1 );
SET i = i+1;
END WHILE;
END $$$
DELIMITER ;
-- 触发器 trigger ,管理图书被借出后，藏书和读者信息的维护
-- 表中数据相关的操作： 增 删 改 （查）
-- 一个表中某条记录被修改：OLD 代表原有的那条记录 NEW代表新的那条记录
-- [BEFORE | AFTER] [INSERT | UPDATE | (DELETE) ]
DELIMITER $$$
CREATE TRIGGER before_insert_loan
BEFORE INSERT ON lib_loan
FOR EACH ROW
BEGIN
-- OLD NEW 已知
DECLARE v1 CHAR(100);
DECLARE v2 INT;
SET NEW.latest =DATE_ADD(NEW.check_out,INTERVAL 1 month);
-- 只能修改NEW
SELECT stat INTO v1
FROM lib_books
WHERE id=NEW.which;
SELECT borrowed INTO v2
FROM readers
WHERE id=NEW.who;
IF ( v1"在馆" ) THEN
SIGNAL SQLSTATE '45000'
SET MESSAGE_TEXT = "图书已借出！";
END IF ;
IF (v2=@READER_MAX) THEN
SIGNAL SQLSTATE '45000'
SET MESSAGE_TEXT = "读者已经到达最大借阅数！";
END IF ;
END $$$
DELIMITER ;
-- 书借出的数据维护
DELIMITER $$$
CREATE TRIGGER after_insert_loan
AFTER INSERT ON lib_loan
FOR EACH ROW
BEGIN
UPDATE lib_books
SET stat = "已借出"
WHERE id = NEW.which ;
UPDATE readers
SET borrowed = borrowed + 1
WHERE id = NEW.who;
END $$$
DELIMITER ;
-- 书归还的数据维护
DELIMITER $$$
CREATE TRIGGER after_update_loan
AFTER UPDATE ON lib_loan
FOR EACH ROW
BEGIN
IF(OLD.check_in is NULL AND NEW.check_in is NOT NULL) THEN
UPDATE lib_books
SET stat="在馆"
WHERE id= NEW.which;
UPDATE readers
SET borrowed=borrowed -1
WHERE id=OLD.who;
END IF;
END $$$
DELIMITER ;
DELIMITER $$$
CREATE TRIGGER before_update_loan
BEFORE UPDATE ON lib_loan
FOR EACH ROW
BEGIN
DECLARE x INT;
IF(OLD.renew=0 AND NEW.renew=1 ) THEN
SET NEW.latest=DATE_ADD(OLD.latest,INTERVAL 1 month);
END IF;
-- 计算超期费用
IF(OLD.check_in is NULL AND NEW.check_in is NOT NULL) THEN
SET x=DATEDIFF(NEW.check_in,NEW.latest);
IF(x=0 )THEN
SET NEW.fee =0 ;
ELSE
SET NEW.fee=@EVERY_DAY_FEE*x;
END IF;
END IF;
END $$$
DELIMITER ;
-- 添加若干的测试数据
INSERT INTO books (name, price)
VALUES
("javascript程序设计", 19.8),
("数据库系统开发", 20.8),
("mysql数据库必知必会", 28.8);
INSERT INTO readers ( name )
VALUES
("Alice"),
("Bob"),
("Carl");
-- 测试语句
SHOW TABLES;
-- 根据书的信息添加10本馆藏图书
CALL add_books( 10) ;
SELECT * from lib_books;
-- 借书
-- 2号读者借了2号书
INSERT INTO lib_loan (who , which ) VALUES (2,2);
INSERT INTO lib_loan (who , which ) VALUES (2,3);
INSERT INTO lib_loan (who , which ) VALUES (2,4);
INSERT INTO lib_loan (who , which ) VALUES (1,2);
INSERT INTO lib_loan (who , which ) VALUES (1,6);
INSERT INTO lib_loan (who , which ) VALUES (2,1);
INSERT INTO lib_loan (who , which ) VALUES (1,1);
-- 还书
UPDATE lib_loan
SET check_in='2022-12-15 12:00:00'
WHERE id = 1;
-- 续借
UPDATE lib_loan
SET renew = 1
WHERE id = 4;
SELECT * FROM lib_books;
SELECT * FROM readers;
SELECT * FROM lib_loan;
用java编写一个 图书馆图书借阅管理系统
---------------------------------------------------
给你修改了三个地方：
1.borrowBooks方法中，将System.out.println("你要借吗？"); 改为：
System.out.println("你要借吗？输入1表示借，其他数字表示不借。");
保证输入的时候输入的数字，否则会报出异常。
2.borrowBooks方法中，将self[score] = all[9]; 改为：self[score] = all[i];
如果是all[9]，那么就始终是最后一本书籍信息了。
3.have方法中，你是想将所借的书籍信息都打印出来。修改的比较多，下面注释代码是原来的。
void have(Books[] self) {
// for (int i = 0; i 2; i++) {
// self[i].showBookInfo();
// }
for (int i = 0; i 3; i++) {
if(self[i]!=null)
self[i].showBookInfo();
}
}
****************** 附上所有代码：*************************
import java.util.Scanner;
public class TestBook {
public static void main(String[] args) {
Books all[] = new Books[10];
Books self[] = new Books[3];
all[0] = new Books("java", 1, "12345", "tom", 34.0f, "人民出版社");
all[1] = new Books("c", 2, "12346", "tnn", 31.0f, "人民出版社");
all[2] = new Books("c++", 3, "12445", "mm", 35.0f, "人民出版社");
all[3] = new Books("c#", 4, "12365", "tt", 38.0f, "人民出版社");
all[4] = new Books("j2se", 5, "13345", "tosm", 31.1f, "人民出版社");
all[5] = new Books("j2ee", 6, "18345", "ttm", 32.0f, "人民出版社");
all[6] = new Books("jsp", 7, "12335", "cc", 33.0f, "人民出版社");
all[7] = new Books("net", 8, "12341", "bb", 36.0f, "人民出版社");
all[8] = new Books("ip", 9, "12343", "aa", 37.0f, "人民出版社");
all[9] = new Books("tcp", 10, "22345", "jj", 39.0f, "人民出版社");
Readers r = new Readers("xiaoming", 101, "1", 3);
r.searchAllBooks(all);
r.borrowBooks(all, self);
r.have(self);
r.give(all, self);
}
}
class Readers {
Scanner scan = new Scanner(System.in);
String names;
int nums;
String classes;
int grade;
int score = 0;
// Books self[]=new Books[3];
Readers(String n, int u, String c, int g) {
names = n;
nums = u;
classes = c;
grade = g;
}
void searchAllBooks(Books[] all) {// 查书
for (int i = 0; i 10; i++)
all[i].showBookInfo();
// self[score]=all[0];
}
void give(Books[] all, Books[] self) {// 还书
System.out.println("请输入您要还的书的书号");
int n = scan.nextInt();
for (int i = 0; i 10; i++) {
if (n == all[i].num) {
for (int j = 0; j 3; j++) {
if (self[j] == all[i]) {
self[j] = null;
System.out.println("还书成功");
}
}
}
}
}
void have(Books[] self) {
// for (int i = 0; i 2; i++) {
// self[i].showBookInfo();
// }
for (int i = 0; i 3; i++) {
if(self[i]!=null)
self[i].showBookInfo();
}
}
void giveMoney() {
}
void borrowBooks(Books[] all, Books[] self) {
System.out.println("请输入您要查找的书名：");
String n = scan.next();
int i;
for (i = 0; i 10; i++) {
if (n.equals(all[i].name)) {
all[i].showBookInfo();
break;
}
}
//System.out.println("你要借吗？");
System.out.println("你要借吗？输入1表示借，其他数字表示不借。");
int j;
j = scan.nextInt();
if (j == 1) {
System.out.println("借阅成功");
//self[score] = all[9];
self[score] = all[i];
score += 1;
}
if (score 4) {
System.out.println("您还可以借阅" + (3 - score) + "本");
} else {
System.out.println("对不起，一个人只能借3本");
}
}
}
class Books {
String name;
int num;
String ISBN;
String writer;
float price;
String publisher;
Books(String n, int u, String i, String w, float p, String l) {
name = n;
num = u;
ISBN = i;
writer = w;
price = p;
publisher = l;
}
void showBookInfo() {
System.out.println("**************************");
System.out.println("书名：" + name);
System.out.println("索书号：" + num);
System.out.println("ISBN号：" + ISBN);
System.out.println("价格：" + price);
System.out.println("出版社：" + publisher);
System.out.println("**************************");
}
}
----------------------------------------------------
java 简单的借书还书代码怎么写
switch(key){
case 1:
//借书
break;
case 2:
//还书
break;
}
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