Thread: Help determining which day a particular date falls on.

So for this project, we have to calculate which day of the week a particular date falls. For example, given 11/3/2012, you would need to find out on which day March 11th falls. (It goes dd/mm/year).

the ArrayList named Rob contains all the tokenized values of the inputs, which are imported from a text file. (An example input would be 12/4/1992,19/3/1996)

I have calculated whether or not a certain year is a leap year, and I have calculated on which day of the week January 1st falls. I am stuck at the part where I determine the which day of the week a particular date falls when given the information that I have already found.

How would I determine which day of the week a date (such as 20/7/1966) falls?

What do I need to add to the code to make this happen?



PS - Everything up to this point works properly.

import java.util.*;
import java.io.*;
 
public class DayOfTheWeek {
 
 
private static PrintWriter out;
private static Scanner in;
private static int integer;
private int year;
private static int intDay;
private static int intMonth;
private static int [] temp;
private static int numDays;
 
 
public static void main (String [] args) { 
 
 
int [] monthlength = new int [] {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
boolean leapYear;
 
 
try{
 
FileInputStream fstream = new FileInputStream("input.txt");
// Get the object of DataInputStream
 
 
DataInputStream in = new DataInputStream(fstream);
BufferedReader br = new BufferedReader(new InputStreamReader(in));
String strLine;
 
 
//Read File Line By Line
while ((strLine = br.readLine()) != null) { 
 
//split it using /and , as the delimiter
 
StringTokenizer st = new StringTokenizer(strLine);
st = new StringTokenizer(strLine, "/,");
while (st.hasMoreElements()) {
 
 
String token = st.nextToken();
integer = Integer.parseInt(token);
rob.add(integer);
}
}
 
 
 
 
 
 
for (int i = 2; i < rob.size(); i+=3) {
 
 
int temp = rob.get(i);
int y = (temp-1);
int x = (36 + y + (y/4) - (y/100) + (y/400)) % 7;
int daysinYear = 365;
 
 
 
if (rob.get(i) % 400 == 0) {
leapYear = true;
daysinYear = (daysinYear + 1);
}
 
else if ((rob.get(i) %4 == 0) && (rob.get(i) %100 != 0)) {
leapYear = true;
daysinYear = (daysinYear + 1);
}
 
else {
leapYear = false;
 
}
 
if (x == 0) {
System.out.println("January first is a Sunday.");
System.out.println(temp);
}
if (x == 1) {
System.out.println("January first is a Monday.");
System.out.println(temp);
}
if (x == 2) {
System.out.println("January first is a Tuesday.");
System.out.println(temp);
}
if (x == 3) {
System.out.println("January first is a Wendsay.");
System.out.println(temp);
}
if (x == 4) {
System.out.println("January first is a Thursday.");
System.out.println(temp);
}
if (x == 5) {
System.out.println("January first is a Friday.");
System.out.println(temp);
}
if (x == 6) {
System.out.println("January first is a Saturday.");
System.out.println(temp);
}
 
 
 
}
 
 
FileWriter output = new FileWriter(args[0]);
PrintWriter out = new PrintWriter(output);
 
 
// Write text to file
out.println("This is line 1");
out.println("This is line 2");
out.println("this is line 3 part 2");
out.close();
 
 
//Close the input stream
in.close();
}
 
catch (Exception e){
System.err.println("Error: " + e.getMessage());
}
}
}

The easiest way would be to first assign a number to each day of the week.(1-7) Then find how many days are in between the current day and the future
date. Then mod by 7. That will give you the day of the week.