Using ArrayDeque Java

Question

I'm trying to store a list of primes using java and came across ArrayDeque. I'm not sure if this is the correct occasion to use it, but since I don't know the number of primes I need the capacity to grow.

The code is designed to go through numbers 2 to 1000 and test if they are a prime or not.

I'm getting some errors. I am pretty new to this so if anybody could guide me in the right direction that would be great. Is using a Array with a large pre-set capacity a better way of doing things?

Many thanks, Behzad

import java.util.ArrayDeque;
import java.util.Deque;

public class Maths {
public static void main (String[] arg) {        

    int x = 2;
    ArrayDeque<integer> primes = new ArrayDeque<integer>(8);

    for(int count = 2; count<1000; count++) {
        if (x%count == 0) {
            System.out.println("Number is not prime"); // If it isn't a prime, it moves onto the next number.
            x = x + 1;
            count = 2;
        }

        else if (x >1000) {
            break;
        }

        else if (count == x - 1) {
            System.out.println( x + " is a prime"); //This possibility singles out prime numbers
            primes.add(x);
            x = x + 1;                              // Need to find a way to add them to memory.
            count = 2;
        }
    }
    System.out.println("Searchfinished");
    System.out.println(primes);
}
}

java has no integer. The primitive is int, the object is Integer. — Menno
– Menno, Commented May 10, 2013 at 9:16
Also, "getting some errors" is no help to us. Please provide the errors. — Menno
– Menno, Commented May 10, 2013 at 9:16
Array deques have no capacity restrictions; they grow as necessary to support usage — Subhrajyoti Majumder
– Subhrajyoti Majumder, Commented May 10, 2013 at 9:17
I think the whole implementation of finding prime numbers is not correct! — hamid
– hamid, Commented May 10, 2013 at 9:21

Konstantin Yovkov · Accepted Answer · 2014-12-10 15:53:04Z

3

There's no thing in Java like integer. The proper one is Integer.

import java.util.ArrayDeque;
public class MyClass {
  public static void main(String args[]) {

    int x = 2;
    Deque<Integer> primes = new ArrayDeque<Integer>(8);

    for(int count = 2; count<1000; count++) {
      if (x%count == 0) {
          System.out.println("Number is not prime"); // If it isn't a prime, it moves onto the next number.
          x = x + 1;
          count = 2;
      } else if (x > 1000) {
          break;
      } else if (count == x - 1) {
          System.out.println( x + " is a prime"); //This possibility singles out prime numbers
          primes.add(x);
          x = x + 1;                              // Need to find a way to add them to memory.
          count = 2;
      }
  }
  System.out.println("Searchfinished");

  System.out.println(primes);
 }
}

edited Dec 10, 2014 at 15:53

answered May 10, 2013 at 9:19

Konstantin Yovkov

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1 Comment

djangofan Over a year ago

Wouldn't this be more correct: Deque<Integer> primes = new ArrayDeque<>(8); ???

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