登录验证demo

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public static void main(String[] args) {
    String rightname = "zhangsan";
    String rightpassword = "123";
    Scanner sc = new Scanner(System.in);
    for (int i = 0; i < 3; i++) {
        //共有三次机会
        System.out.println("请输入用户名：");
        String username = sc.next();
        System.out.println("请输入密码：");
        String password = sc.next();
        if (username.equals(rightname) && password.equals(rightpassword)) {
            System.out.println("登录成功！");
            break;
        } else {
            if (i == 2) {
                System.out.println(username + "已被锁定请联系管理员进行操作！");
            } else {
                System.out.println("登录失败" + "你还剩" + (2 - i) + "次机会！");
            }
        }
    }
}

数字转换

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public static void main(String[] args) {
    //键盘先录入 判断是否合法
    Scanner sc = new Scanner(System.in);
    int money;
    while (true) {
        System.out.println("请输入金额：");
        money = sc.nextInt();
        if (money >= 0 && money <= 9999999) {
            break;
        } else {
            System.out.println("输入不合法，请重新输入！");
        }
    }
    //定义一个变量记录金额
    String moneyStr = "";
    while (true) {
        int ge = money % 10;
        String number = getCapitalNumber(ge);
        moneyStr = number + moneyStr;
        money = money / 10;
        if (money == 0) {
            break;
        }
    }
    System.out.println(moneyStr);
    //补零操作
    int count = 7 - moneyStr.length();
    for (int i = 0; i < count; i++) {
        moneyStr = "零" + moneyStr;
    }
    System.out.println(moneyStr);
    //插入单位
    String result = "";
    String[] arr = {"佰", "拾", "万", "千", "佰", "拾", "元"};
    for (int i = 0; i < moneyStr.length(); i++) {
        char ch = moneyStr.charAt(i);
        result = result + ch + arr[i];
    }
    System.out.println(result);
}

//数字与大写字母相对应
public static String getCapitalNumber(int number) {
    String[] arr = {"零", "壹", "贰", "叁", "肆", "伍", "陆", "柒", "捌", "玖"};
    return arr[number];
}

数字拼接

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public static void main(String[] args) {
    int[] arr = {1, 2, 3, 4, 5, 43, 21};
    System.out.println(ArrToString(arr));
}
public static String ArrToString(int[] arr) {
    StringBuilder sb = new StringBuilder();
    sb.append("[");
    for (int i = 0; i < arr.length; i++) {
        if (i == arr.length - 1) {
            sb.append(arr[i]);
        } else {
            sb.append(arr[i] + ",");
        }
    }
    sb.append("]");
    return sb.toString();
}