JavaSE_Java

练习知识点：
java类，面向对象，抽象类，接口，封装，继承，多态，顺序表

练习通过封装抽象类user以及操作接口来实现多态，目的是将图书管理人员和普通用户区分开,以及将不同权限的人操作区分开.

文章目录

1.书籍，书架包
- 书籍类
- 书架类
2.操作包
- 操作接口
- 增加
- 删除
- 显示
- 查找
- 借阅
- 归还
- 退出
3.用户管理包
- 用户抽象类
- 超级用户
- 普通用户
4.主函数，程序入口
5.代码位置

1.书籍，书架包书籍类

package book;

public class Book {
    private String name;
    private String author;
    private double price;
    private String type;
    private boolean isBorrow;

    public Book(String name, String author, double price, String type) {
        this.name = name;
        this.author = author;
        this.price = price;
        this.type = type;
        this.isBorrow = false;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public boolean isBorrow() {
        return isBorrow;
    }

    public void setBorrow(boolean borrow) {
        isBorrow = borrow;
    }

    @Override
    public String toString() {
        return "Book{" +
                "name='" + name + ''' +
                ", author='" + author + ''' +
                ", price=" + price +
                ", type='" + type + ''' +
                (this.isBorrow ?", 已借出":", 未借出")+
                '}';
    }
}

书架类

package book;

import java.util.Arrays;

public class BookList {
    private Book[] books;
    private int usenum;//书本个数
    private int capacity;

    public Book[] getBooks() {
        return books;
    }

    public BookList(){
        this.books=new Book[]{new Book("小王子","安托万·德·圣-埃克苏佩",34.5,"童话")};
        usenum=1;
        capacity=1;
    }

    public int getUsenum() {
        return usenum;
    }

    public int findBook(String name){
        for(int i=0;i
            if(books[i].getName().equals(name)){
               return i;
            }
        }
        return -1;
    }

    public void setUsenum(int usenum) {
        this.usenum = usenum;
    }

    public Book GetPos(int pos){
        if(pos>usenum){
            return null;
        }
        return this.books[pos];
    }

    public void addBook(Book book){
        if(usenum==capacity){
            this.books=Arrays.copyOf(this.books,2*capacity);
            capacity*=2;
            System.out.println("扩容成功");
        }
        this.books[usenum]=book;
        usenum++;
    }
}

2.操作包操作接口

package operation;

import book.BookList;

public interface Operation {
    void work(BookList bookList);
}

增加

package operation;

import book.Book;
import book.BookList;

import java.util.Scanner;

public class AddOperation implements Operation{
    public void work(BookList booklist){
        String name;String author;double price;String type;
        Scanner io=new Scanner(System.in);
        System.out.println("书名:");
        name=io.nextLine();
        System.out.println("作者: ");
        author=io.nextLine();
        System.out.println("书籍类型: ");
        type=io.nextLine();
        System.out.println("价格: ");
        price=io.nextDouble();
        Book book=new Book(name,author,price,type);
        booklist.addBook(book);

        System.out.println("添加图书成功！");
        //System.out.println(booklist.getUsenum());
    }
}

删除

package operation;

import book.Book;
import book.BookList;

import java.util.Scanner;

public class DelOperation implements Operation{
    public void work(BookList booklist){
        Scanner io=new Scanner(System.in);
        System.out.println("输入要删除的书名:");
        String name=io.nextLine();
        int pos=booklist.findBook(name);
        Book[] books=booklist.getBooks();
        if(pos!=-1){
            int size=booklist.getUsenum();
            for (int i = pos; i < size-1; i++) {
                books[i] = books[i + 1];
            }
            booklist.setUsenum(size-1);
            System.out.println("删除成功");
        }
        else{
            System.out.println("没有找到"+name+"这本书");
        }
    }
}

显示

package operation;

import book.BookList;

public class DisplayOperation implements Operation{
    public void work(BookList booklist){
        int size=booklist.getUsenum();
        if(size==0){
            System.out.println("书架为空");
            return;
        }
        for(int i=0;i
            System.out.println(booklist.GetPos(i));
        }
    }
}

查找

package operation;

import book.BookList;

import java.util.Scanner;

public class FindOperation implements Operation{
    public void work(BookList booklist){
        Scanner io=new Scanner(System.in);
        int size=booklist.getUsenum();
        if(size==0){
            System.out.println("书架为空!");
            return;
        }
        System.out.println("输入要查找的书名: ");
        String name=io.nextLine();
        int pos=booklist.findBook(name);
        if(pos!=-1){
            System.out.println(booklist.GetPos(pos));
        }
        else{
            System.out.println("没找到这本书!!");
        }
    }
}

借阅

package operation;

import book.BookList;

import java.util.Scanner;

public class FindOperation implements Operation{
    public void work(BookList booklist){
        Scanner io=new Scanner(System.in);
        int size=booklist.getUsenum();
        if(size==0){
            System.out.println("书架为空!");
            return;
        }
        System.out.println("输入要查找的书名: ");
        String name=io.nextLine();
        int pos=booklist.findBook(name);
        if(pos!=-1){
            System.out.println(booklist.GetPos(pos));
        }
        else{
            System.out.println("没找到这本书!!");
        }
    }
}

归还

package operation;

import book.BookList;

import java.util.Scanner;

public class ReturnOperation implements Operation{
    public void work(BookList booklist){
        System.out.println("输入要归还的书籍");
        String name=new Scanner(System.in).nextLine();
        int pos=booklist.findBook(name);
        if(pos!=-1){
            booklist.GetPos(pos).setBorrow(false);
            System.out.println("归还成功");
        }
        else{
            System.out.println("书库无"+name+"这本书的存储记录");
        }
    }
}

退出

package operation;

import book.BookList;

public class ExitOperation implements Operation{
    public void work(BookList booklist){
        System.out.println("退出系统");
        System.exit(0);
    }
}

3.用户管理包用户抽象类

package user;

import book.BookList;
import operation.Operation;

import java.util.Scanner;

public abstract class User {//抽象类
    protected String name;
    protected Scanner choice;
    protected Operation[] operation;

    public User(String name){
        this.name=name;
        choice=new Scanner(System.in);
    }

    public void SelectWork(int op, BookList booklist){
        this.operation[op].work(booklist);
    }

    public abstract int menu();
}

超级用户

package user;

import operation.*;

public class AdminUser extends User{

    public AdminUser(String name) {
        super(name);
        this.operation=new Operation[]{new ExitOperation(),new FindOperation(),new AddOperation()
                ,new DelOperation(),new DisplayOperation()
        };

    }

    public int menu(){
        System.out.println("Hello Admin "+this.name+": ");
        System.out.println("=====管理员菜单=====");
        System.out.println("1.查找图书");
        System.out.println("2.新增图书");
        System.out.println("3.删除图书");
        System.out.println("4.显示图书");
        System.out.println("0.退出系统");
        System.out.println("=================");
        return choice.nextInt();
    }
}

普通用户

package user;

import operation.*;

import java.util.Scanner;

public class NormalUser extends User{

    public NormalUser(String name){
        super(name);
        this.operation=new Operation[]{new ExitOperation(),new FindOperation(),new BorrowOperation()
                ,new ReturnOperation(),new DisplayOperation()
        };
    }

    public int menu(){
        System.out.println("Hello User "+this.name+": ");
        System.out.println("=====操作菜单=====");
        System.out.println("1.查找图书");
        System.out.println("2.借阅图书");
        System.out.println("3.归还图书");
        System.out.println("4.显示图书");
        System.out.println("0.退出系统");
        System.out.println("================");
        return choice.nextInt();
    }
}

4.主函数，程序入口

//程序入口

import book.BookList;
import user.AdminUser;
import user.NormalUser;
import user.User;

import java.util.Scanner;

public class main {
    public static User login(){
        System.out.println("输入用户姓名");
        Scanner io=new Scanner(System.in);
        String name=io.nextLine();
        System.out.println("输入用户权限 1:管理员 0:普通用户");
        int choice=io.nextInt();
        if(choice==0||choice==1) {
            if (choice == 1) {
                return new AdminUser(name);
            }
            else{
                return new NormalUser(name);
            }
        }
        else{
            System.out.println("用户权限错误，退出程序");
            return null;
        }
    }
    public static void main(String[] args) {
        BookList bookList=new BookList();
        User user=login();//向上转型
        while(user!=null) {
            int choice = user.menu();//动态绑定
            user.SelectWork(choice, bookList);
        }
    }
}

5.代码位置

Github

Gitee

JavaSE

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