Question

I have a program that calculates whether or not a date entered by a user is a leap year or not. I think I got that all down but I also need to see if the date that is entered is a binary date (i.e. 1/1/11. I’m not really sure the best way to go about this, maybe an charAt reference? Any help would be must appreciated!

//****************************
import java.util.Scanner;

public class leapYearCalc {
private int day = 0;
private int month = 0;
private int year = 0;
Scanner myScan = new Scanner (System.in);


//---------------------------------
//Constructor to accept and initialize instance data
//---------------------------------
public leapYearCalc(int day, int month, int year){
this.day=day;
this.month=month;
this.year=year;
}

//--------------------------------
//Get day
//--------------------------------
public int getDay(){
    System.out.println("Whats the day?");
    day = myScan.nextInt();
    return day;
}

//--------------------------------
//Get day
//--------------------------------
public int getMonth(){
    System.out.println("Whats the month in numerical form?");
    month = myScan.nextInt();
    return month;
}

//--------------------------------
//Get day
//--------------------------------
public int getYear(){
    System.out.println("Whats the year (i.e. 2004)?");
    year = myScan.nextInt();
        if (year<1582)
            System.out.println("Please enter a value above 1582");
    return year;
}


//--------------------------------
 //1. If a year is divisible by 4 it is a leap year if 2 does not apply.
 //2. If a year is divisible by 100 it is not a leap year unless #3 applies.
 //3. If a year is divisible by 400 it is a leap year.
//--------------------------------
//Calculate leap year   
public String toString() {
        if (year % 4 == 0) {
            if (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.");
            }
        }
        else {
            System.out.println(year + " is not a leap year.");
        }
        return null;
    }

    //--------------------------------
    //Check to see if date is binary
    //--------------------------------
    public int getBinary(){
        while(month == 01 || month == 10)

            if(day == 01 || day == 10 && year == 00 || year == 01)
                System.out.println("It's a binary date!");
        System.out.println("It's not a binary date");
        return month;

    }
}

Answer 1

So you are checking if the day, month and year fields are either 1, 10 0r 11. If they are then it is a binary date, otherwise it is not a binary date. Maybe your getBinary() method should simply return a boolean value. You do not need a while loop there, rather an if statement would work:

public boolean getBinary(){
    if(month == 1 || month == 10 || month == 11){
        if(day == 1 || day == 10 || day = 11){
              if(year == 0 || year == 1 || year == 10 || year == 11){
                 return true;
              }

     }
     return false;
}

In addition your leap year calculation can be simplified if you start with the divisible by 400. e.g.

  if(year is divisible by 400)
      leap year
  else
      if year is divisible by 100 then
         not a leap year
      else
           if year is divisble by 4 then
              leap year
           else
              not a leap year

or it can all be made into a simple boolean expression like this

 if(year is divisible by 400 or (year is not divisble by 100 and divisible by 4))
        leap year
 else
        not leap year

===================
Considering a four digit year then you could split each digit off like this:

     int num = year; //to preserve the original year value
     int digit = num / 1000; //get first digit
     //check if digit is 0 or 1
     num = num % 1000; //remove first digit
     digit = num / 100; //get second digit
     //check if digit is 0 or 1
     num = num % 100;//remove second digit
     etc