Prime Numbers

Java Code

/**
 * PrimeNumbersToFile.java
 * Created by Stijn Strickx on Oct. 7 2005
 * Copyright 2005 Stijn Strickx, All rights reserved
 */

import java.io.*;
public class PrimeNumbersToFile{
public static void main(String[] arguments) throws java.io.IOException {

	int number;
	long maxnumber = 0;
	int divider;
	int breakteller = 0;
	boolean prime;
	double rootnumber;

		maxnumber = getNumber("At which number should the program stop searching for further prime numbers? ");

	try {	
	FileOutputStream fos = new FileOutputStream("PrimeNumbersFile.txt");
	PrintStream ps = new PrintStream(fos);
	ps.print(2 + " ");
	
		for (number = 3; number <= maxnumber; number = number+2){
		rootnumber = Math.sqrt(number);
		prime=true;

			for (divider = 3; prime && (divider <= rootnumber); divider = divider+2)
				if((number%divider) == 0)
					prime = false;
				else{
					prime = true;
				}

			if(prime){
			breakteller = breakteller+1;
			ps.print(number + " ");

				if(breakteller == 20){
				ps.println();
				breakteller = 0;
				}
			}
		}
	System.out.print("You can now access the PrimeNumbersFile.txt which is ");
	System.out.println("in the same directory as the .class file of this program.");
	ps.close();
	} catch (FileNotFoundException e)
		{ System.err.println("error writing to file" + e);
			}
	}
	
	static long getNumber(String question) throws java.io.IOException {
		String theNumber;
		long number = 0;
		BufferedReader in = new BufferedReader (new InputStreamReader(System.in));
		System.out.print(question);
		theNumber = in.readLine();
		System.out.println();
		number = Long.parseLong(theNumber);
		return number;
	}
}