对伙伴徐鹏的代码检查

他的代码

import java.util.Scanner;

    public class calendar {
        public static void main(String[] args) {
            for (int g = 0; g < 100; g++) {
                Scanner in = new Scanner(System.in);
                System.out.println("
请输入年份：");
                int year = in.nextInt();
                System.out.println("请输入月份：");
                int month = in.nextInt();
                int sum = 0;
                int k = 0;
                for (int i = 1; i <= month - 1; i++) {
                    if (i == 2) {
                        if (year % 4 == 0 && year % 100 != 0 || year % 400 == 0) {
                            sum = sum + 29;
                        } else {
                            sum = sum + 28;
                        }
                    } else {
                        if (i == 4 || i == 6 || i == 9 || i == 11) {
                            sum = sum + 30;
                        } else {
                            sum = sum + 31;
                        }
                    }
                }
                for (int a = 1900; a <= year - 1; a++) {
                    if (a % 4 == 0 && a % 100 != 0 || a % 400 == 0) {
                        sum = sum + 366;
                    } else {
                        sum += 365;
                    }
                }
                sum += 1;
                int wekday = sum % 7;
                System.out.println("日	一	二	三	四	五	六");
                for (int j = 1; j <= wekday; j++) {
                    System.out.print("	");
                }
                if (year % 4 == 0 && year % 100 != 0 || year % 400 == 0) {
                    if (month == 2) {
                        k = 29;
                    } else if (month == 4 || month == 6 || month == 9 || month == 11) {
                        k = 30;
                    } else {
                        k = 31;
                    }
                } else {
                    if (month == 2) {
                        k = 28;
                    } else if (month == 4 || month == 6 || month == 9 || month == 11) {
                        k = 30;
                    } else {
                        k = 31;
                    }
                }
                for (int i = 1; i <= k; i++) {
                    if (sum % 7 == 6) {
                        System.out.print(i + "
");
                    } else {
                        System.out.print(i + "	");
                    }
                    sum++;
                }
            }
        }
    }

我感觉的不足之处