Why doesn't my date validation code work?

Question

my code doesn't return any value and i have no idea why. My assignment requires me to write a code that accepts date in mm/dd/yyyy format and im required to put leap year in. The problem is, i dont get back any input. Im an amateur ad i dont know what is wrong. Im also allowed to use Case statement but I'm not sure how to implement case.
The problem i hvae is, there is no input. Literally non.

import java.util.Scanner;
public class Question1 {

public static void main(String[] args) {

Scanner sc = new Scanner(System.in).useDelimiter("/");
System.out.println("Please enter a date in mm/dd/yyyy format: ");
String mm = sc.next();
String dd = sc.next();
String yyyy = sc.next();
int month = Integer.parseInt(mm);
int day = Integer.parseInt(dd);
int year = Integer.parseInt(yyyy);

if (month <= 0 && month>12)
{
System.out.println("invalid month ");
}
if (year%4 != 0 && month == 02 && day >= 29)
{
System.out.println("invalid date");
}
if (month == 4 && month == 6 && month == 9 && month == 11 && day >= 31)
{
System.out.println("Invalid day");
}
if (month == 1 && month == 3 && month == 5 && month == 7 && month == 8 && month == 10 && month == 12 && day >=32 )
{
System.out.println("Invalid day");
}
else
{
System.out.println("Valid date");
}
}
}

Answer 1

You need to trim off the trailing whitespace from yyyy and/or add \n as a delimiter.

int month = Integer.parseInt(mm);
int day = Integer.parseInt(dd);
int year = Integer.parseInt(yyyy.trim());

The program will run once this whitespace is removed. However, you may also want to revisit your logic in your if statements. ie (month == 4 && month== 6 etc) Will never be true. Wrap the months in parentheses and || or them then && the day.

Answer 2

The Dawg is right.

From a real world standpoint:
What should happen at : -1/0/1983?

If you want to impress whoever is grading that:
The leap rule is somewhat more complicated, since Pope Gregory.
There is no year 0. The 0 wasn't invented, when the calendar was made.
Weird things happen in 1583.