制作日历时格式化字符串打印输出

Question

My code is below, it doesn't format right, the days if the month are one big line. Not how a calendar should be does anyone see formatting errors? As well as can someone explain to me how the leap year checker works, i had to look it up and for the life of me cant figure out how and why it works? Thanks!

package calendaryear;
import java.util.Scanner;
public class CalendarYear {

/**
 * @param args the command line arguments
 */
public static void main(String[] args) {
    String month;
    String day;
    Scanner userinput = new Scanner(System.in);
    //enter the day!
    System.out.print("Enter day [0 is for Sunday, 1 is for moneday continued]:");
    int d = userinput.nextInt();
    //enter a year!
    System.out.print("Enter a year:");
    int y = userinput.nextInt();
    // for loop for 12 months!
    for (int m = 1; m <= 12; m++){
        switch (m) {
            case 1:
                month = "January";
                break;
            case 2:
                month = "February";
                break;
            case 3:
                month = "March";
                break;
            case 4:
                month = "April";
                break;
            case 5:
                month = "May";
                break;
            case 6:
                month = "June";
                break;
            case 7:
                month = "July";
                break;
            case 8:
                month = "August";
                break;
            case 9:
                month = "September";
                break;
            case 10:
                month = "October";
                break;
            case 11:
                month = "November";
                break;
            case 12:
                month = "December";
                break;
            default:
                month ="";
                }

        System.out.printf("%" + (34 + month.length()) / 2 + "s %s\n", month, y);
        System.out.println(String.format("%39S", "").replace(' ', '-'));
        System.out.printf("%-6s%-6s%-6s%-6s%-6s%-6s%-6s\n", "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat");

        int l = 30 + ((m + (int)(m / 8.0)) % 2);
        if (m == 2) {
            if ((y % 4 == 0 && y % 100 != 0) || (y % 400 == 0)){
                l = 29;
            }else {
                l = 28;
            }
        }
        d = (d) % 7;
        switch (d) {
            case 0:
                day = "Sunday";
                break;
            case 1:
                day = "Moneday";
                break;
            case 2:
                day = "Tuesday";
                break;
            case 3:
                day = "Wednesday";
                break;
            case 4:
                day = "Thursday";
                break;
            case 5:
                day = "Friday";
                break;
            case 6:
                day = "Saturday";
                break;
            default:
                day = "";
        }
        if (d != 0) {
            System.out.print(String.format("%" + 6 * d + "s", ""));

        }

        for (int i = 1; i<= l; i++){
            System.out.printf("%-6d", i);
            if (d % 7 == 6){
                System.out.print("");
            }
            day += 1;





        }
        System.out.print("");


    }
}

}

Answer 1

For leap year: Added solution

Didn't understand what you are trying to achieve in for-loop, what exactly is the issue?

 public void leapYear(int year)
    {
        System.out.println("This program calculates leap year.");
         if ((year % 4 == 0) && year % 100 != 0)
        {
            System.out.println(year + " is a leap year.");
        }
        else if (year % 400 == 0)
        {
            System.out.println(year + " is a leap year.");
        }
        else
        {
            System.out.println(year + " is not a leap year.");
        }
    }

Answer 2

Your problem is in the for loop at the bottom of the class. You mean to check the current value of 'i', which you are incrementing when doing the if condition and not the variable 'd', which is not changing on each iteration of the loop.

Try this modification:

       for (int i = 1; i<= l; i++){
            System.out.printf("%-6d", i);
            if (i % 7 == 6){
                System.out.println();
            }
            day += 1;
        }