prime number : Sieve of Eratosthenes

import java.io.BufferedReader; import java.io.InputStreamReader;

class test4 {

public static void main(String[] args)throws Exception {


    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

    int t = Integer.parseInt(br.readLine());

     int N = 1000000000;

    // initially assume all integers are prime
    boolean[] isPrime = new boolean[N+1];
    for (int i = 2; i <= N; i++) {
        isPrime[i] = true;
    }

    // mark non-primes <= N using Sieve of Eratosthenes
    for (int i = 2; i*i <= N; i++) {

        // if i is prime, then mark multiples of i as nonprime
        // suffices to consider mutiples i, i+1, ..., N/i
        if (isPrime[i]) {
            for (int j = i; i*j <= N; j++) {
                isPrime[i*j] = false;
            }
        }
    }
     isPrime[1] = false;
    while(t-->0)
    {

        String str[];
        str=br.readLine().split(" ");
        int m=Integer.parseInt(str[0]);
        int n=Integer.parseInt(str[1]);

        for(int i=m;i<=n;i++)
        {
            if(i%2==0&&i!=2)
            {
                continue;
            }
            if(isPrime[i])
            {
                System.out.println(i);
            }
        }


    }



}

} i am getting the following error Exception in thread "main" java.lang.OutOfMemoryError: Java heap space in my net beans and runtime error in code chef on this line :boolean[] isPrime = new boolean[N+1]; how can i remove it or do i have to use different algorithm ??