Mersenne primes: Difference between revisions

=={{header|Java}}==

{{trans|Kotlin}}

<lang Java>import java.math.BigInteger;

public class MersennePrimes {

private static final int MAX = 20;

private static final BigInteger ONE = BigInteger.ONE;

private static final BigInteger TWO = BigInteger.valueOf(2);

private static boolean isPrime(int n) {

if (n < 2) return false;

if (n % 2 == 0) return n == 2;

if (n % 3 == 0) return n == 3;

int d = 5;

while (d * d <= n) {

if (n % d == 0) return false;

d += 2;

if (n % d == 0) return false;

d += 4;

}

return true;

}

public static void main(String[] args) {

int count = 0;

int p = 2;

while (true) {

BigInteger m = TWO.shiftLeft(p - 1).subtract(ONE);

if (m.isProbablePrime(10)) {

System.out.printf("2 ^ %d - 1\n", p);

if (++count == MAX) break;

}

// obtain next prime, p

while (true) {

p = (p > 2) ? p + 2 : 3;

if (isPrime(p)) break;

}

}

}

}</lang>

{{out}}

<pre>2 ^ 2 - 1

2 ^ 3 - 1

2 ^ 5 - 1

2 ^ 7 - 1

2 ^ 13 - 1

2 ^ 17 - 1

2 ^ 19 - 1

2 ^ 31 - 1

2 ^ 61 - 1

2 ^ 89 - 1

2 ^ 107 - 1

2 ^ 127 - 1

2 ^ 521 - 1

2 ^ 607 - 1

2 ^ 1279 - 1

2 ^ 2203 - 1

2 ^ 2281 - 1

2 ^ 3217 - 1

2 ^ 4253 - 1

2 ^ 4423 - 1</pre>