Java基礎黑馬程式員教材 案例2.3、2.6代碼詳解

一、2.3超市購物程式

import java.util.Scanner;

public class test2_3 {
    //超市購物程式
  static   double cash=0.0;
    public  static double buy(){
        System.out.println("你要買什么？輸入id");
        Scanner scanner=new Scanner(System.in);
        int id=1;
        id=scanner.nextInt();
        System.out.println("買多少份？");
        int num=scanner.nextInt();
        switch (id){
            default:
                System.out.println("輸入的不是商品號");
                break;
            case  1:
                cash+=8.8*num;
                break;
            case 2:
                cash+=10.0*num;
                break;
            case 3:
                cash+=18.8*num;
                break;
            case 4:
                cash+=12.5*num;
                break;
            case 5:
                cash+=15.5*num;
        }
        return  cash;
    }
    public static void main(String[] args) {
        buy();

        Scanner scanner=new Scanner(System.in);
        String choicey="Y";
        String choicen="N";
        System.out.println("還要買嗎？要買輸入Y，不買輸入N");
        String ch=scanner.nextLine();
        if(ch.equals(choicey)){
             cash=buy();
        }
        else if(ch.equals(choicen)){
            System.out.println("總共花了"+cash);
            System.exit(1);
        }
        System.out.println("總共花了"+cash);
    }
}

二、2.6登陸注冊

import java.util.HashMap;
import java.util.Scanner;

public class test2_6 {
 static    HashMap<Integer,String> message=new HashMap<>();
public  static void login(){
    System.out.println("這里是登陸界面");
    System.out.println("請輸入賬號密碼");
    Scanner scanner=new Scanner(System.in);
   int number=scanner.nextInt();
    Scanner scanner1=new Scanner(System.in);
    String password=scanner1.nextLine();
    if(message.get(number).equals(password)){
        System.out.println("登陸成功");
    }
    else {
        System.out.println("密碼不對哦，或者賬號不存在");
    }
}
public  static void register(){
    System.out.println("這里是注冊界面");
    System.out.println("請輸入賬號和密碼一行一個，賬號不能重復,長度僅限6位數");
    System.out.println("tips:賬號純數字，密碼你隨意");
    System.out.println("先輸入賬號吧，寶兒");
    Scanner scanner=new Scanner(System.in);
    int  number=scanner.nextInt();
    System.out.println("輸密碼");
    Scanner scanner1=new Scanner(System.in);
    String password=scanner1.nextLine();
    message.put(number, password);

}
public static void check(){

    System.out.println(message);

}
public  static void exit(){
System.exit(0);
}
    public static void main(String[] args) {

        while (true){
            System.out.println("這里是登陸注冊案例");
            System.out.println("請選擇要做的操作：");
            System.out.println("1.登陸");
            System.out.println("2.注冊");
            System.out.println("3.查看");
            System.out.println("4.退出");
            Scanner scanner=new Scanner(System.in);
            int choice=scanner.nextInt();
            switch (choice){
                default:
                    System.out.println("選錯了，再來");
                    break;
                case 1:
                    login();
                    break;
                case 2:
                    register();
                    break;
                case 3:
                    check();
                    break;
                case 4:
                    exit();
                    break;
            }
        }

    }
}