Bit lost with doing a ratio

[Ryan Bishop]

Hi,

I'm doing a problem where I create two files (one in Word and one in notepad) with the same movie quote. I then have to create an application
saying if they exist and if they do show their file sizes and ratio of them. I think I'm fine with the file sizes but I don't know
how to get a ratio other than dividing one by the other, in which case quote1/quote2 gives a 0 and the reverse gives 44,
which leads to me not having any idea how to do an actual ratio like 3:2 or whatever.
Is this even remotely the right way to go about it? The issue is at line 17.
Thanks for any advice.

import java.io.File;

public class FileStatistics2 {

	public static void main(String[] args) {

		File quote1 = new File("c:\\Users\\adam\\My Documents\\moviequote.txt");
		
		File quote2 = new File("c:\\Users\\adam\\My Documents\\moviequote2.docx");

		if (quote1.exists() && quote2.exists())
	    {
	       System.out.println("Yes, the files exist and the size of the\n first file is "
	    		   + quote1.length() + " while the size\n of second is " 
	    		   + quote2.length() + ".");
	       System.out.println("The ratio of the two file sizes is "
	    		   + (quote2.length()/quote1.length()) + ".");  // Is there a better way to calculate their ratio?
	         
	    }
	    else
	       System.out.println("Sorry, but the file does not exist.");
	 
	 }
	}

[Steve Kedzie]

Ryan,

Are you sure the problem actaully wants you to divide the lengths and not just display them like quote1.length : quote2.length? Commonly, a ratio represents a comparison of the size of two values.

Steve

[Ryan Bishop]

Yeah, I think you're right. I saw a few examples browsing the web and that seems to be how they do it.

Is it standard to convert the length to kilobytes? I saw one person do something like below rather
than the length of the original:

double quote1size = quote1.length();
			double quote2size = quote2.length();
			
			double size1kb = quote1size/1024;
			double size2kb = quote2size/1024;

[Steve Kedzie]

The conversion you saw was probbaly a personal choice or it could have been a requirement by a client or instructor.

[Campbell Ritchie]

The conversion you had originally may go horribly wrong. If I remember correctly length() returns a long, so you are using integer arithmetic; if you divide 387465983746L by 387465983747L, you get zero. If you divide the other way round, you get one; you also get one from dividing 774931967491L by 387465983746L.

I would suggest for your kB calculations you use the % operator too. Don't use 1024 which is a “magic number”; it equals 0x400.

long quote1size = quote1.length();
long quote2size = quote2.length();
int BYTES_IN_KB = 0x400; // With 00 at the end in hex you have exact multiple of 256.			
long size1kb = quote1size/BYTES_IN_KB + (quote1size % BYTES_IN_KB == 0 ? 0 : 1);
long size2kb = quote2size/BYTES_IN_KB + (quote2size % BYTES_IN_KB == 0 ? 0 : 1);

That will give you the size inwhole numbers of kB but round up to return 1 from a 0.1kB file. If you are using % with an exact power of 2 you can use
((quote1size & BYTES_IN_KB - 1) == 0 ? 0 : 1)
instead, if you understand the strange‑looking syntax.

You may suffer imprecision for large files because the precision of a long is greater than a double's for large values of long.

[Campbell Ritchie]

Thank you for the cow, whoever gave it