从面向过程到面向对象来进行增删改查
private static void libraryDemo() {
String[] bookNames = {"《西游记》", "《红楼梦》", "《水浒传》", "《三国演义》"};
String[] bookAuthor = {"吴承恩", "曹雪芹", "施耐庵", "罗贯中"};
double[] bookPrice = {50, 45, 30, 55};
Study study = new Study();
String inputName;
int repeatIndex;
boolean flag = true;
while (flag) {
System.out.println("1、添加图书");
System.out.println("2、修改图书");
System.out.println("3、删除图书");
System.out.println("4、查看图书");
System.out.println("0、退出系统");
int choice = InputUtil.intRegex("请选择您要使用的功能：", "^[0-4]{1}");
switch (choice) {
case 1:
System.out.println("-->添加图书");
String answer;
do {
System.out.println("请输入需要添加的图书名称：");
inputName = input.next();
repeatIndex = study.repeat(inputName, bookNames);
if (repeatIndex == -1) {
bookNames = Arrays.copyOf(bookNames, bookNames.length + 1);
bookNames[bookNames.length - 1] = inputName;
System.out.println("请输入" + inputName + "的作者");
bookAuthor = Arrays.copyOf(bookAuthor, bookNames.length);
bookAuthor[bookAuthor.length - 1] = input.next();
System.out.println("请输入" + inputName + "的价格");
bookPrice = Arrays.copyOf(bookPrice, bookNames.length);
bookPrice[bookPrice.length - 1] = input.nextDouble();
System.out.println("添加成功");
} else System.out.println("图书已存在！");
System.out.println("请问是否继续添加图书？y/n");
answer = input.next();
} while ("y".equals(answer) || "Y".equals(answer));
break;
case 2:
System.out.println("-->修改图书");
System.out.println("请输入需要修改的图书名称");
inputName = input.next();
repeatIndex = study.repeat(inputName, bookNames);
if (repeatIndex == -1) {
System.out.println("图书不存在！请重新输入");
} else {
System.out.println("请输入修改之后的图书名称");
bookNames[repeatIndex] = input.next();
System.out.println("请输入" + bookNames[repeatIndex] + "的作者");
bookAuthor[repeatIndex] = input.next();
System.out.println("请输入" + bookNames[repeatIndex] + "的价格");
bookPrice[repeatIndex] = input.nextDouble();
System.out.println("修改成功！");
}
break;
case 3:
System.out.println("-->删除图书");
System.out.println("请输入需要删除的图书名称");
inputName = input.next();
repeatIndex = study.repeat(inputName, bookNames);
if (repeatIndex == -1)
System.out.println("图书不存在");
else {
for (int i = repeatIndex; i < bookNames.length - 1; i++) {
bookNames[i] = bookNames[i + 1];
bookAuthor[i] = bookAuthor[i + 1];
bookPrice[i] = bookPrice[i + 1];
}
bookNames = Arrays.copyOf(bookNames, bookNames.length - 1);
bookAuthor = Arrays.copyOf(bookAuthor, bookNames.length - 1);
bookPrice = Arrays.copyOf(bookPrice, bookNames.length - 1);
System.out.println("删除成功！");
}
break;
case 4:
System.out.println("-->查看图书");
System.out.println("图书名称\t 作者名\t图书价格");
for (int i = 0; i < bookAuthor.length; i++) {
System.out.print(bookNames[i] + "\t");
System.out.print(bookAuthor[i] + "\t");
System.out.print(bookPrice[i] + "\t");
System.out.println();
}
break;
case 0:
System.out.print("-->退出系统");
flag = false;
break;
}
}
}
private int repeat(String name, String[] bookNames) {
int index = 0;
for (String bookName : bookNames) {
if (bookName.equals(name)) {
return index;//相同书籍的索引值
}
index++;
}
return -1;//不存在这本书
}
下面我们用面向对象的形式来重新写这个功能：（一些方法我用的是lombok插件里面的注解写的，不清楚的可以看我之前的博客）
分析业务，实体层—>图书，操作层—>使用图书馆，业务层—>增删改查
实体对象类：
@Setter
@Getter
@ToString
public class Book {
private int id;
private String name;
private double price;
private String author;
private String publisher;
private static int identity = 1000;
public Book(String name, double price, String author, String publisher) {
id=identity++;
this.name = name;
this.price = price;
this.author = author;
this.publisher = publisher;
}
public Book() {
id = identity++;
}
}
操作层：
public class BookAction {
private static Scanner input;
private static BookService bookService;
private static Book[] books = new Book[3];
static {
books[0] = new Book("西游记", 36, "liku", "出版社");
books[1] = new Book("红楼梦", 55, "liku", "出版社");
books[2] = new Book("三国演义", 78, "liku", "出版社");
}
public static void startMenu() {
bookService = new BookService();
input = new Scanner(System.in);
boolean b = true;
while (b) {
System.out.println("欢迎来到liku图书馆，请选择您需要进行的操作：");
System.out.println("1、查看图书");
System.out.println("2、修改图书");
System.out.println("3、删除图书");
System.out.println("4、增加图书");
System.out.println("0、退出系统");
int choice = input.nextInt();
switch (choice) {
case 1:
bookService.show(books);
break;
case 2:
bookService.update(books);
break;
case 3:
books= bookService.minus(books);
break;
case 4:
books=bookService.add(books);
break;
case 0:
System.out.println("谢谢惠顾！欢迎下次光临！");
b = false;
break;
}
}
}
}
业务层：
public class BookService {
private static Scanner input = new Scanner(System.in);
public void show(Book[] books) {
System.out.println("现有图书信息如下：");
for (Book book : books) {
System.out.println(book);
}
}
public Book[] add(Book[] books) {
Book book = new Book();
System.out.println("请输入需要添加图书名称：");
book.setName(input.next());
System.out.println("请输入需要添加图书的价格：");
book.setPrice(input.nextDouble());
System.out.println("请输入需要添加图书的作者：");
book.setAuthor(input.next());
System.out.println("请输入需要添加图书的出版社：");
book.setPublisher(input.next());
books = Arrays.copyOf(books, books.length + 1);
books[books.length - 1] = book;
return books;
}
public Book[] minus(Book[] books) {
System.out.println("请输入需要删除的图书名称：");
String name = input.next();
int index = exit(name,books);
if (index == -1) {
System.out.println("删除失败！图书不存在");
return books;
}
for (int i = index; i < books.length-1; i++) {
books[i] = books[i + 1];
}
books = Arrays.copyOf(books, books.length - 1);
System.out.println("删除成功！");
return books;
}
private int exit(String name,Book[] books) {
int index;
for (int i = 0; i < books.length; i++) {
if (books[i].getName().equals(name)) {
index = i;
return index;
}
}
return -1;
}
public void update(Book[] books) {
System.out.println("请输入需要修改的图书名称：");
String name = input.next();
int index = exit(name,books);
if (index == -1) {
System.out.println("修改失败！图书不存在");
return;
}
Book book=books[index];//因为没有new，因此是将地址里面的值给更改，是有效的
System.out.println("请输入修改后的图书名称：");
book.setName(input.next());
System.out.println("请输入修改后的图书价格：");
book.setPrice(input.nextDouble());
System.out.println("请输入修改后的图书作者：");
book.setAuthor(input.next());
System.out.println("请输入修改后的图书出版社：");
book.setPublisher(input.next());
}
}
利用面向对象，我们可以清晰的将每个过程独立开来，代码就变得很清晰，代码还是要多敲，才会理解并掌握
