Can some on help me optimize my code such that it can use less memory & be efficient

[thatos]

The following program was supposed to read a number of years from a file called "friday.in" then print out how many of the thirteenth were on each day from monday to sunday on to a file called "friday.out ". Here is the code which I used .

import java.io.*;
import java.util.*;
public class friday{
	public static void main(String args[]) throws IOException{
		
		BufferedReader in = new BufferedReader(new FileReader("friday.in"));
		PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter("friday.out")));
		int mon,tue,wed,thu,fri,sat,sun;
		mon = tue = wed = thu = fri = sat = sun = 0;
		int day = 13;
		int year = 1900;
		int years = Integer.parseInt(in.readLine());
		while (year < year + years){
				int numday;
				int tot;
				int month = 1;
				switch (month){
				case 1:tot = 31;break;
				case 2:tot = (((year % 4)==0) || ((year % 100) == 0))?29:28;break;					
				case 3:tot = 31;break;
				case 4:tot = 30;break;
				case 5:tot = 31;break;
				case 6:tot = 30;break;
				case 7:tot = 31;break;
				case 8:tot = 31;break;
				case 9:tot = 30;break;
				case 10:tot = 31;break;
				case 11:tot = 30;break;
				case 12:tot = 31;break;
				default:tot = 31;				
				}
				if (((year % 4)==0) || ((year % 100) == 0)){					
					numday = 366;
				}
				else{					
					numday = 365;
				}
				while (month <= 12){
					int cat = day % 7;
					if (cat == 1){
						mon++;
						}
					else if (cat == 2){
						tue++;
						}
					else if (cat == 3){
						wed++;
						}
					else if (cat == 4){
						thu++;
						}
					else if (cat == 5){
						fri++;
						}
					else if (cat == 6){
						sat++;
						}
					else{
						sun++;
						}
					day += tot;
					month++;
					}
				day = day % numday;
				year++;
				}
		out.write(sat+" "+sun+" "+mon+" "+tue+" "+wed+" "+thu+" "+fri+"\n");
		out.close();
		System.exit(0);
		}
}

The above code takes a long time to give an output and uses much more memory.

[thatos]

Here is the new version it runs quite fast but gives wrong values

import java.io.*;
import java.util.*;
public class friday{
	
	static int year = 1900;//The initial year
	
	//This method return the number of days in each month
	public static int getNumDay(int month){
		int tot;
		switch (month){
		case 1:tot = 31;break;
		case 2:tot = (((year % 4)==0) || (((year % 100) == 0) && (year % 400 == 0)))?29:28;break;					
		case 3:tot = 31;break;
		case 4:tot = 30;break;
		case 5:tot = 31;break;
		case 6:tot = 30;break;
		case 7:tot = 31;break;
		case 8:tot = 31;break;
		case 9:tot = 30;break;
		case 10:tot = 31;break;
		case 11:tot = 30;break;
		case 12:tot = 31;break;
		default:tot = 31;				
		}
		return tot;
	}
	public static void main(String args[]) throws IOException{
		
		BufferedReader in = new BufferedReader(new FileReader("E:/friday.in"));
		PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter("E:/friday.out")));
		int mon,tue,wed,thu,fri,sat,sun;
		mon = tue = wed = thu = fri = sat = sun = 0;
		int day = 13;//The initial day		
		int years = Integer.parseInt(in.readLine());//The number of years
		int totalYears = year + years - 1;
		while (year < totalYears){
				int numday;				
				int month = 1;
				//Calculates the number of days in that year
				if (((year % 4)==0) || ((year % 100) == 0)){					
					numday = 366;
				}
				else{					
					numday = 365;
				}
				while (month <= 12){
					int cat = day % 7;
					if (cat == 1){
						mon++;
						}
					else if (cat == 2){
						tue++;
						}
					else if (cat == 3){
						wed++;
						}
					else if (cat == 4){
						thu++;
						}
					else if (cat == 5){
						fri++;
						}
					else if (cat == 6){
						sat++;
						}
					else{
						sun++;
						}
					day += getNumDay(month);
					month++;
					}
				day = numday % day;
				year++;
				}
		out.write(sat+" "+sun+" "+mon+" "+tue+" "+wed+" "+thu+" "+fri+"\n");
		out.close();
		System.exit(0);
		}
}

[thatos]

Latest version

import java.io.*;
import java.util.*;
public class friday{
	
	static int year = 1900;//The initial year
	public static boolean isLeapYear(int year){
		if ((year % 100 == 0)){
			if ((year % 400) == 0){
				return true;
			}
			else {
				return false;
			}
			}
		else if((year % 4) == 0){
			return true;
		}
		else{
			return false;} 
	}
	
	//This method return the number of days in each month
	public static int getNumDay(int month){
		int tot;
		switch (month){
		case 1:tot = 31;break;
		case 2:if (isLeapYear(year) == true){
			tot = 29;
		}else{
			tot = 28;
		}
			break;					
		case 3:tot = 31;break;
		case 4:tot = 30;break;
		case 5:tot = 31;break;
		case 6:tot = 30;break;
		case 7:tot = 31;break;
		case 8:tot = 31;break;
		case 9:tot = 30;break;
		case 10:tot = 31;break;
		case 11:tot = 30;break;
		case 12:tot = 30;break;
		default:tot = 31;break;				
		}
		return tot;
	}
	public static void main(String args[]) throws IOException{
		
		BufferedReader in = new BufferedReader(new FileReader("friday.in"));
		PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter("friday.out")));
		int mon,tue,wed,thu,fri,sat,sun;
		mon = tue = wed = thu = fri = sat = sun = 0;
		int day = 13;//The initial day		
		int years = Integer.parseInt(in.readLine());//The number of years
		int totalYears = year + years;
		int numday;
		while (year < totalYears){
								
				int month = 1;
				
				//Calculates the number of days in that year
				if (isLeapYear(year) == true){
					numday = 366;
				}
				else{
					numday = 365;
				}
				while (month <= 12){
					int cat = day % 7;
					if (cat == 1){
						mon++;
						}
					else if (cat == 2){
						tue++;
						}
					else if (cat == 3){
						wed++;
						}
					else if (cat == 4){
						thu++;
						}
					else if (cat == 5){
						fri++;
						}
					else if (cat == 6){
						sat++;
						}
					else{
						sun++;
						}
					day += getNumDay(month);
					month++;
					}
				day += numday;
				year++;
				}
		out.write(sat+" "+sun+" "+mon+" "+tue+" "+wed+" "+thu+" "+fri+"\n");
		out.close();
		System.exit(0);
		}
}

[JosAH]

Why don't you use a GregorianCalend ar and leave those nasty details to
that class? In the outer loop you set the year, the inner loop sets the months
and the day (13) and all you have to do is update the day counters.

kind regards,

Jos

ps. I don't like large main() methods.

[thatos]

Why don't you use a GregorianCalend ar and leave those nasty details to
that class? In the outer loop you set the year, the inner loop sets the months
and the day (13) and all you have to do is update the day counters.

kind regards,

Jos

ps. I don't like large main() methods.

I was requested not to use any java build in function of time to write a program which will compute this, nut any way I finaly fiqured out were my problem was.

[JosAH]

I was requested not to use any java build in function of time to write a program which will compute this, nut any way I finaly fiqured out were my problem was.

You should have googled a bit more; I did and I found pages about Zeller's
congruence: a simple formula that calculates the Julian day number also used
by the Gregorian calendar class. I hacked a bit and cooked up this:

[code=java]
public static int dayOfWeek(int y, int m, int d) {

d+=(m<3)?y--:y-2;
return (23*m/9+d+4+y/4-y/100+y/400)%7;
}
[/code]

This little method returns 0 == Sun, 1 == Mon, ... 6 == Sat. Have fun with it.

kind regards,

Jos