Java-Programs/SieveOfEratosthenes.java at master · Scarlet-Coder/Java-Programs · GitHub

History

74 lines (63 loc) · 1.72 KB

Raw

public class SieveOfEratosthenes {

private static int limit = 1000; // Only used if no value passed through.

private static boolean[] booleanArray;

private static int totalPrimes;

private static long calcTime;

public static void main(String[] args)

{

long startTime = System.currentTimeMillis();

setup(args);

findAllPrimes();

displayPrimes();

long endTime = System.currentTimeMillis();

long timeTaken = endTime - startTime;

System.out.println();

System.out.println("It took " + calcTime + "ms to calculate the prime numbers below " + limit + ".");

System.out.println("The complete algorithm took " + timeTaken + "ms to finish.");

System.out.println();

System.out.println("There are " + totalPrimes + " prime numbers below " + limit + ".");

}

private static void setup(String[] args)

{

if(args.length > 0)

{

limit = Integer.parseInt(args[0]);

}

booleanArray = new boolean[limit + 1];

for(int position = 0; position <= limit; position++)

{

booleanArray[position] = false;

}

private static void findAllPrimes()

{

long calcStartTime = System.currentTimeMillis();

for(int position = 2; position <= Math.sqrt(limit); position++)

{

if(booleanArray[position] == false)

{

int multiple = position * 2;

while(multiple <= limit)

{

booleanArray[multiple] = true;

multiple += position;

}

long calcEndTime = System.currentTimeMillis();

calcTime = calcEndTime - calcStartTime;

}

private static void displayPrimes()

{

for(int position = 2; position <= limit; position++)

{

if(booleanArray[position] == false)

{

totalPrimes++;

System.out.print(position + ", ");

}

Java-Programs/SieveOfEratosthenes.java at master · Scarlet-Coder/Java-Programs · GitHub

Expand file tree

Breadcrumbs

SieveOfEratosthenes.java

Latest commit

History

Breadcrumbs

SieveOfEratosthenes.java

File metadata and controls