java_零钱通_面向过程版本

package change;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Scanner;

public class Change {
    public static void main(String[] args) {
        boolean loop = true;
        Scanner scanner = new Scanner(System.in);
        String key = "";

        // 明细
        String details = "-------------明细--------------\n";

        // 入账
        double money = 0;
        double balance = 0;
        Date date = null;
        // 将获取的时间格式化成我们想要的格式
        SimpleDateFormat tf = new SimpleDateFormat("yyyy-MM-dd HH:mm"); 

        // 消费
        String note = "";

        do {
            System.out.println("=========零钱通=========");
            System.out.println("\t\t\t1 明细");
            System.out.println("\t\t\t2 入账");
            System.out.println("\t\t\t3 消费");
            System.out.println("\t\t\t4 退出");
            System.out.print("请选择(1-4): ");
            key = scanner.next();

            switch(key){
                case "1" :
                    System.out.println(details);
                    break;
                case "2" :
                    System.out.print("请输入您的金额：");
                    money = scanner.nextDouble();
                    if (money <= 0) {
                        System.out.println("金融应该大于0哦");
                        break;
                    }
                    balance += money;
                    date = new Date();
                    details += "入账金额" + "\t" + money + "\t"
                            + tf.format(date) + "\t" + "余额"
                            + "\t" + balance + "\n";
                    break;
                case "3" :
                    System.out.print("消费金额: ");
                    money = scanner.nextDouble();
                    if (money <= 0 || money > balance) {
                        System.out.println("金额的范围是 0 - " + balance);
                        break;
                    }
                    balance -= money;
                    System.out.print("消费说明：");
                    note = scanner.next();
                    date = new Date();
                    details += note + "\t" + money + "\t"
                            + tf.format(date) + "\t" + "余额"
                            + "\t" + balance + "\n";
                    break;
                case "4" :
                    String choice = "";
                    while (true){
                        System.out.println("您确定要退出吗？y/n");
                        choice = scanner.next();
                        if ("y".equals(choice) || "n".equals(choice)){
                            break;
                        }
                    }
                    if (choice.equals("y")){
                        loop = false;
                    }
                    break;
                default:
                    System.out.println("输入有误，请重新输入");
            }
            System.out.println("++++++++++++++++++++++++++++++++");
        }while(loop);
        System.out.println("您已经退出零钱通系统");
    }
}