PrimeSum.java

public class PrimeSum {
    static boolean isPrime(Integer x){
    	if(x==2)
    		return true;
    	if(x%2==0)
    		return false;
        for(Integer j=2;j<=Math.sqrt(x);j++){
        	if(x%j==0)
        		return false;
        }
        return true;
    }
	public static void main(String[] args) {
	   Long sum =(long) 0;
	   for(Integer i=2;i<1500000;i++){
		   if(isPrime(i))
			   sum+=i;
	   }
      System.out.println(sum);
	}
}

Citing to this Line-16, i=i+2 will make the loop twice faster