如何在java中使用SQL实现接口Comparable，Collection.sort（）？
这是一个简单的库项目。它必须通过要求用户基于关键字或体裁进行搜索，从数据库加载数据。 我有两节课。其中之一是图书班如何在java中使用SQL实现接口Comparable，Collection.sort（）？,java,database,sorting,comparator,compareto,Java,Database,Sorting,Comparator,Compareto,这是一个简单的库项目。它必须通过要求用户基于关键字或体裁进行搜索，从数据库加载数据。 我有两节课。其中之一是图书班 包库； 导入java.sql.Date； 公共类书{ 字符串标题； 字符串作者； 日期； 字符串ISBN； 字符串格式； 字符串发布器； 浮动价格； 字符串[]关键字； 字符串[]输入阵列； 字符串输入； 公共图书（字符串标题参数、字符串作者参数、java.util.Date日期参数、字符串ISBN参数、， 字符串格式参数、字符串发布者参数、浮动价格参数、字符串关键字参数）{ ti
包库；
导入java.sql.Date；
公共类书{
字符串标题；
字符串作者；
日期；
字符串ISBN；
字符串格式；
字符串发布器；
浮动价格；
字符串[]关键字；
字符串[]输入阵列；
字符串输入；
公共图书（字符串标题参数、字符串作者参数、java.util.Date日期参数、字符串ISBN参数、，
字符串格式参数、字符串发布者参数、浮动价格参数、字符串关键字参数）{
title=title_参数；
作者=作者参数；
日期=（日期）日期参数；
ISBN=ISBN_参数；
格式=格式参数；
publisher=publisher_param；
价格=价格参数；
关键词=关键词参数拆分（“，”）；
}
public void setUserInput（字符串userIn）{
输入=用户输入；
}
private int getRelevance（字符串用户输入）{
inputArray=userInput.split（“，”）；
int num=0；
for（int i=0；i！=keywords.length；i++）{
字符串in=inputArray[i]；
for（int l=0；l！=keywords.length；l++）{
if（in.equals（关键字[l]））
num++；
}
}
返回num；
}
公共国际比较（o册）{
if（this.getRelevance（输入）>o.getRelevance（输入））{
返回1；
}else if（this.getRelevance（输入） package library;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Date;
import java.util.Scanner;
public class LibrarySearch {
static ArrayList<Book> books = new ArrayList<Book>();
ArrayList<LibrarySearch> genres = new ArrayList<LibrarySearch>();
static ArrayList<LibrarySearch> keywords = new ArrayList<LibrarySearch>();
public static void main(String[] args) {
load_data();
}
private static void load_data() {
Collections.sort(books, new Comparator<Book>() {
@Override
public int compare(Book first, Book second) {
if (first.compareTo(second) == 1) {
return 1;
} else if (first.compareTo(second) == -1) {
return -1;
}
return 0;
}
});
Connection connection = null;
Statement statement = null;
try {
Class.forName("com.mysql.jdbc.Driver");
connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/library", "root", "123456");
statement = connection.createStatement();
System.out.println("Choose to search by keywords or genres");
Scanner scanner = new Scanner(System.in);
String input = scanner.nextLine();
if (input.equals("keywords")) {
System.out.println("Enter your keywords: ");
String[] keyWordsInput = scanner.nextLine().split(",");
ResultSet result = null;
for (int i = 0; i != keyWordsInput.length; i++) {
result = statement
.executeQuery(" SELECT * FROM book WHERE keywords LIKE '%" + keyWordsInput[i] + "%'");
}
while (result.next()) {
int id = result.getInt("id");
String title = result.getString("title");
String author = result.getString("author");
Date date = result.getDate("date");
String ISBN = result.getString("ISBN");
String format = result.getString("format");
String publisher = result.getString("publisher");
float price = result.getFloat("price");
String keywords = result.getString("keywords");
System.out.println("ID = " + id);
System.out.println("TITLE = " + title);
System.out.println("AUTHOR = " + author);
System.out.println("DATE = " + date);
System.out.println("ISBN = " + ISBN);
System.out.println("FORMAT = " + format);
System.out.println("PUBLISHER = " + publisher);
System.out.println("PRICE = " + price);
System.out.println("KEYWORDS = " + keywords);
System.out.println("___________________________________________________________________________");
if (title.equals("I,Robot")) {
Book new_book = new Book(title, author, date, ISBN, format, publisher, price, keywords);
books.add(new_book);
}
if (title.equals("Catch-22")) {
Book new_book1 = new Book(title, author, date, ISBN, format, publisher, price, keywords);
books.add(new_book1);
}
if (title.equals("Pride and Prejudice")) {
Book new_book2 = new Book(title, author, date, ISBN, format, publisher, price, keywords);
books.add(new_book2);
}
if (title.equals("Gone with the Wind")) {
Book new_book3 = new Book(title, author, date, ISBN, format, publisher, price, keywords);
books.add(new_book3);
}
}
result.close();
statement.close();
connection.close();
} else if (input.equals("genres")) {
System.out.println("Enter your genres" + ": ");
String genresInput = scanner.nextLine();
ResultSet result = statement.executeQuery(
" SELECT * FROM books_genres JOIN book ON (book.id = books_genres.book_id) JOIN genre ON (genre.id = books_genres.genre_id) WHERE name LIKE '%"
+ genresInput + "%' ");
while (result.next()) {
int id = result.getInt("id");
String name = result.getString("name");
int book_id = result.getInt("book_id");
int genre_id = result.getInt("genre_id");
int id1 = result.getInt("id");
String title = result.getString("title");
String author = result.getString("author");
Date date = result.getDate("date");
String ISBN = result.getString("ISBN");
String format = result.getString("format");
String publisher = result.getString("publisher");
float price = result.getFloat("price");
String keywords = result.getString("keywords");
System.out.println("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
System.out.println("Book ID = " + id1);
System.out.println("TITLE = " + title);
System.out.println("AUTHOR = " + author);
System.out.println("DATE = " + date);
System.out.println("ISBN = " + ISBN);
System.out.println("FORMAT = " + format);
System.out.println("PUBLISHER = " + publisher);
System.out.println("PRICE = " + price);
System.out.println("KEYWORDS = " + keywords);
System.out.println("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
System.out.println("Genre ID = " + id);
System.out.println("Genre Name = " + name);
System.out.println("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
System.out.println("Book ID = " + book_id);
System.out.println("Genre ID = " + genre_id);
}
result.close();
statement.close();
connection.close();
}
else {
System.out.println("Sorry, wrong command");
}
} catch (SQLException ex) {
System.out.println("No successful connection");
System.out.println("SQLException: " + ex.getMessage());
System.out.println("SQLState: " + ex.getSQLState());
}
catch (ClassNotFoundException x_not_found) {
System.out.println("Class not found");
}
}
}
包库；
导入java.sql.Connection；
导入java.sql.DriverManager；
导入java.sql.ResultSet；
导入java.sql.SQLException；
导入java.sql.Statement；
导入java.util.ArrayList；
导入java.util.Collections；
导入java.util.Comparator；
导入java.util.Date；
导入java.util.Scanner；
公共类图书馆搜索{
静态ArrayList books=新建ArrayList（）；
ArrayList流派=新的ArrayList（）；
静态ArrayList关键字=新建ArrayList（）；
公共静态void main（字符串[]args）{
加载_数据（）；
}
专用静态空隙荷载_数据（）{
Collections.sort（图书、新比较器（）{
@凌驾
公共整数比较（第一册，第二册）{
如果（第一个比较到（第二个）==1）{
返回1；
}else if（第一个。比较到（第二个）=-1）{
返回-1；
}
返回0；
}
});
连接=空；
Statement=null；
试一试{
Class.forName（“com.mysql.jdbc.Driver”）；
connection=DriverManager.getConnection（“jdbc:mysql://localhost:3306/library“，”根“，”123456”）；
statement=connection.createStatement（）；
System.out.println（“选择按关键字或类型搜索”）；
扫描仪=新的扫描仪（System.in）；
字符串输入=scanner.nextLine（）；
if（输入.等于（“关键字”））{
System.out.println（“输入关键字：”）；
String[]关键字输入=scanner.nextLine（）.split（“，”）；
ResultSet result=null；
for（int i=0；i！=关键字input.length；i++）{
结果=语句
.executeQuery（“从书中选择*，其中包含“%”+关键字输入[i]+“%”等关键字）；
}
while（result.next（））{
int id=result.getInt（“id”）；
String title=result.getString（“title”）；
String author=result.getString（“author”）；
日期=结果。获取日期（“日期”）；
String ISBN=result.getString（“ISBN”）；
字符串格式=result.getString（“格式”）；
String publisher=result.getString（“publisher”）；
浮动价格=result.getFloat（“价格”）；
字符串关键字=result.getString（“关键字”）；
System.out.println（“ID=”+ID）；
System.out.println（“TITLE=“+TITLE”）；
System.out.println（“AUTHOR=“+AUTHOR”）；
System.out.println（“日期=”+日期）；
System.out.println（“ISBN=“+ISBN”）；
System.out.println（“FORMAT=“+FORMAT”）；
System.out.println（“PUBLISHER=“+PUBLISHER”）；
System.out.println（“PRICE=“+PRICE”）；
System.out.println（“关键字=”+关键字）；
系统.out.println（“uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu；
if（标题等于（“I，机器人”））{
Book new_Book=新书（书名、作者、日期、ISBN、格式、出版商、价格、关键字）；
图书。添加（新图书）；
}
如果（标题等于（“第22条军规”））{
Book new_book1=新书（书名、作者、日期、ISBN、格式、出版商、价格、关键字）；
新增图书（新增图书1）；
}
if（标题等同（“傲慢与偏见”））{
Book new_book2=新书（标题、作者、日期、ISBN、格式、出版商、价格、关键字）；
新增图书（新增图书2）；
}
如果（标题等于（“乱世佳人”））{
Book new_book3=新书（书名、作者、日期、ISBN、格式、出版商、价格、关键字）；
新增图书（新增图书3）；
package library;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Date;
import java.util.Scanner;
public class LibrarySearch {
static ArrayList<Book> books = new ArrayList<Book>();
ArrayList<LibrarySearch> genres = new ArrayList<LibrarySearch>();
static ArrayList<LibrarySearch> keywords = new ArrayList<LibrarySearch>();
public static void main(String[] args) {
load_data();
}
private static void load_data() {
Collections.sort(books, new Comparator<Book>() {
@Override
public int compare(Book first, Book second) {
if (first.compareTo(second) == 1) {
return 1;
} else if (first.compareTo(second) == -1) {
return -1;
}
return 0;
}
});
Connection connection = null;
Statement statement = null;
try {
Class.forName("com.mysql.jdbc.Driver");
connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/library", "root", "123456");
statement = connection.createStatement();
System.out.println("Choose to search by keywords or genres");
Scanner scanner = new Scanner(System.in);
String input = scanner.nextLine();
if (input.equals("keywords")) {
System.out.println("Enter your keywords: ");
String[] keyWordsInput = scanner.nextLine().split(",");
ResultSet result = null;
for (int i = 0; i != keyWordsInput.length; i++) {
result = statement
.executeQuery(" SELECT * FROM book WHERE keywords LIKE '%" + keyWordsInput[i] + "%'");
}
while (result.next()) {
int id = result.getInt("id");
String title = result.getString("title");
String author = result.getString("author");
Date date = result.getDate("date");
String ISBN = result.getString("ISBN");
String format = result.getString("format");
String publisher = result.getString("publisher");
float price = result.getFloat("price");
String keywords = result.getString("keywords");
System.out.println("ID = " + id);
System.out.println("TITLE = " + title);
System.out.println("AUTHOR = " + author);
System.out.println("DATE = " + date);
System.out.println("ISBN = " + ISBN);
System.out.println("FORMAT = " + format);
System.out.println("PUBLISHER = " + publisher);
System.out.println("PRICE = " + price);
System.out.println("KEYWORDS = " + keywords);
System.out.println("___________________________________________________________________________");
if (title.equals("I,Robot")) {
Book new_book = new Book(title, author, date, ISBN, format, publisher, price, keywords);
books.add(new_book);
}
if (title.equals("Catch-22")) {
Book new_book1 = new Book(title, author, date, ISBN, format, publisher, price, keywords);
books.add(new_book1);
}
if (title.equals("Pride and Prejudice")) {
Book new_book2 = new Book(title, author, date, ISBN, format, publisher, price, keywords);
books.add(new_book2);
}
if (title.equals("Gone with the Wind")) {
Book new_book3 = new Book(title, author, date, ISBN, format, publisher, price, keywords);
books.add(new_book3);
}
}
result.close();
statement.close();
connection.close();
} else if (input.equals("genres")) {
System.out.println("Enter your genres" + ": ");
String genresInput = scanner.nextLine();
ResultSet result = statement.executeQuery(
" SELECT * FROM books_genres JOIN book ON (book.id = books_genres.book_id) JOIN genre ON (genre.id = books_genres.genre_id) WHERE name LIKE '%"
+ genresInput + "%' ");
while (result.next()) {
int id = result.getInt("id");
String name = result.getString("name");
int book_id = result.getInt("book_id");
int genre_id = result.getInt("genre_id");
int id1 = result.getInt("id");
String title = result.getString("title");
String author = result.getString("author");
Date date = result.getDate("date");
String ISBN = result.getString("ISBN");
String format = result.getString("format");
String publisher = result.getString("publisher");
float price = result.getFloat("price");
String keywords = result.getString("keywords");
System.out.println("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
System.out.println("Book ID = " + id1);
System.out.println("TITLE = " + title);
System.out.println("AUTHOR = " + author);
System.out.println("DATE = " + date);
System.out.println("ISBN = " + ISBN);
System.out.println("FORMAT = " + format);
System.out.println("PUBLISHER = " + publisher);
System.out.println("PRICE = " + price);
System.out.println("KEYWORDS = " + keywords);
System.out.println("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
System.out.println("Genre ID = " + id);
System.out.println("Genre Name = " + name);
System.out.println("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
System.out.println("Book ID = " + book_id);
System.out.println("Genre ID = " + genre_id);
}
result.close();
statement.close();
connection.close();
}
else {
System.out.println("Sorry, wrong command");
}
} catch (SQLException ex) {
System.out.println("No successful connection");
System.out.println("SQLException: " + ex.getMessage());
System.out.println("SQLState: " + ex.getSQLState());
}
catch (ClassNotFoundException x_not_found) {
System.out.println("Class not found");
}
}
}
public int compareTo(Book o) {
return this.getRelevance(input) - o.getRelevance(input);
}
Collections.sort(books, new Comparator<Book>() {
@Override
public int compare(Book first, Book second) {
return first.compareTo(second);
}
});