day 4 (项目一：家庭收支记录)

 FamilyAccount.java 与 Utility.java放在同一根目录下

//代码如下：

package project01;
public class FamaillyAccount {
    public static void main(String[] arg){
        String details = "收支t账户金额t收支金额t说    明n";
        int balance = 10000;
        boolean loopFlag = true;
        do {
            System.out.println("-----------------家庭收支记账软件-----------------");
            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();
            System.out.println("                 请选择（1-4）:                  ");
            char keyNumber = Utility.readMenuSelection();
            switch (keyNumber){
                case '1':
                    System.out.println("-----------------当前收支明细记录-----------------");
                    System.out.println(details);
                    System.out.println("-----------------------------------------------");
                    break;
                case '2':
                    System.out.println("本次收入金额:");
                    int amount1 = Utility.readNumber();
                    System.out.println("本次收入说明:");
                    String dec1 = Utility.readString();
                    System.out.println("-------------------登记完成--------------------n");
                    balance += amount1;
                    details += "收入" + "t" + balance + "tt" + amount1 + "tt" + dec1 +"n";
                    break;
                case '3':
                    System.out.println("本次支出金额:");
                    int amount2 = Utility.readNumber();
                    System.out.println("本次支出说明:");
                    String dec2 = Utility.readString();
                    balance -= amount2;
                    details += "支出" + "t" + balance + "tt" + amount2 + "tt" + dec2 +"n";
                    System.out.println("-------------------登记完成--------------------n");
                    break;
                case '4':
                    System.out.println("确认是否退出Y/N:");
                    char conf = Utility.readConfirmSelection();
                    break;
            }
        }while (loopFlag);
    }
}

在FamilyAccount.java中使用到的Utility文件代码如下：

import java.util.Scanner;

public class Utility {
    private static Scanner scanner = new Scanner(System.in);
    
	public static char readMenuSelection() {
        char c;
        for (; ; ) {
            String str = readKeyBoard(1);
            c = str.charAt(0);
            if (c != '1' && c != '2' && c != '3' && c != '4') {
                System.out.print("选择错误，请重新输入：");
            } else break;
        }
        return c;
    }
	
    public static int readNumber() {
        int n;
        for (; ; ) {
            String str = readKeyBoard(4);
            try {
                n = Integer.parseInt(str);
                break;
            } catch (NumberFormatException e) {
                System.out.print("数字输入错误，请重新输入：");
            }
        }
        return n;
    }
	
    public static String readString() {
        String str = readKeyBoard(8);
        return str;
    }
	
	
    public static char readConfirmSelection() {
        char c;
        for (; ; ) {
            String str = readKeyBoard(1).toUpperCase();
            c = str.charAt(0);
            if (c == 'Y' || c == 'N') {
                break;
            } else {
                System.out.print("选择错误，请重新输入：");
            }
        }
        return c;
    }
	
	
    private static String readKeyBoard(int limit) {
        String line = "";

        while (scanner.hasNext()) {
            line = scanner.nextLine();
            if (line.length() < 1 || line.length() > limit) {
                System.out.print("输入长度（不大于" + limit + "）错误，请重新输入：");
                continue;
            }
            break;
        }

        return line;
    }
}

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