implements of Sieve of Eratosthenes

import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;

/**
 *
 *
 * implements of Sieve of Eratosthenes
 */
public class PrimeNumbers {
    public static void main(String[] s) {

        long start =1L;
        long end = 5000L;

        long startTime = System.nanoTime();

        Map <Long,Boolean> map = new LinkedHashMap<>();
        map.put(2L, true);

        for (long m  = 3;  m <end; m+=2) {
            map.put(m,true);
        }

        for (long i = 3; i <Math.sqrt(end); i+=2) {

            if(map.get(i)==true){
                long j = 0;
                for (j = i*j; j < end; j+=i) {
                    map.put(j,false);
                }
            }
        }
        Iterator<Long> keys = map.keySet().iterator();
        while(keys.hasNext()){
            Long key = keys.next();
            if(map.get(key)==false || (key<start)){
                keys.remove();
            }
        }
        System.out.println("Total Primes = " +map.size());
        System.out.println(map.keySet());
        System.out.println("Time Taken = " +(System.nanoTime()-startTime)/1000000000 + " Seconds");


    }


}