1.在app下創建名爲model的包，model中建名爲Book的class：
package models;
import java.util.HashSet;
import java.util.Set;
public class Book {
public Integer id;
public String title;
public Integer price;
public String author;
public Book(Integer id,String title,Integer price,String author){
this.id = id;
this.title =title;
this.price = price;
this.author =author;
}
private static Set<Book> books;
static{
books = new HashSet<>();
books.add(new Book(1,"C++",20,"leiyuxing"));
books.add(new Book(2,"JAVA",21,"yangjianwen"));
books.add(new Book(3,"C",22,"wangshiyu"));
}
public static Set<Book> allBooks(){
return books;
}
//通過id查找方法
public static Book findById(Integer id){
for(Book book:books){
if(id.equals(book.id)){
return book;
}
}
return null;
}
//添加書籍
public static void add(Book book){
books.add(book);
}
//刪除書籍
public static boolean remove(Book book){
return books.remove(book);
}
}
