1. 实现效果

2.项目架构

public class Test {public static void main(String[] args) {while(true){System.out.println("-------欢迎使用记账系统--------");System.out.println("1.收支明细");System.out.println("2.登记收入");System.out.println("3.登记支出");System.out.println("4.退出");System.out.println("请输入你要选择的功能：");//拿来一个扫描器Scanner sc = new Scanner(System.in);//接收键盘录入的int类型的数据：int choice = sc.nextInt();//对你录入的choice做一个过滤：while(choice!=1&&choice!=2&&choice!=3&&choice!=4){System.out.println("对不起，你录入的功能错误，请重新录入：");int newChoice = sc.nextInt();choice = newChoice;}//根据你录入的数字，判断执行对应的功能：switch (choice){case 1:System.out.println("记账系统》》》》收支明细");break;case 2:System.out.println("记账系统》》》》登记收入");break;case 3:System.out.println("记账系统》》》》登记支出");break;case 4:System.out.println("记账系统》》》》退出功能");return;//结束当前方法}}}
}

3. 细节代码实现

public class Test {public static void main(String[] args) {//定义一个字符串，用来接收整个收支的明细：String details = "";//定义一个变量，接收余额：int balance = 0; //初始化金额为0元while(true){System.out.println("-------欢迎使用小鲨鱼记账系统--------");System.out.println("1.收支明细");System.out.println("2.登记收入");System.out.println("3.登记支出");System.out.println("4.退出");System.out.println("请输入你要选择的功能：");//拿来一个扫描器Scanner sc = new Scanner(System.in);//接收键盘录入的int类型的数据：int choice = sc.nextInt();//对你录入的choice做一个过滤：while(choice!=1&&choice!=2&&choice!=3&&choice!=4){System.out.println("对不起，你录入的功能错误，请重新录入：");int newChoice = sc.nextInt();choice = newChoice;}//根据你录入的数字，判断执行对应的功能：switch (choice){case 1:System.out.println("记账系统》》》》收支明细");//如果直接输出details，那么最后多了一个换行：//System.out.println(details);/*String s = details.substring(0,details.length()-1);System.out.println(s);*/if(details!=""){System.out.println(details.substring(0,details.length()-1));}else{System.out.print(details);}break;case 2:System.out.println("记账系统》》》》登记收入");System.out.println("请录入收入金额：");int income = sc.nextInt();System.out.println("请录入收入说明：");String incomeDetail = sc.next();balance += income;details = details+"收入："+income+",收入说明："+incomeDetail+",账户余额："+balance+"\n";break;case 3:System.out.println("记账系统》》》》登记支出");System.out.println("请录入支出金额：");int expend = sc.nextInt();System.out.println("请录入支出说明：");String expendDetail = sc.next();balance -= expend;details = details+"支出："+expend+",支出说明："+expendDetail+",账户余额："+balance+"\n";break;case 4:System.out.println("记账系统》》》》退出功能");System.out.println("确定要退出吗？Y/N:");String isExit = sc.next();switch (isExit){case "Y" :System.out.println("系统退出，欢迎您下次继续使用！");return;//结束当前方法}}}}
}