Progo Progo - 1 month ago 12
Java Question

Java compare integer and bigInteger

How do I compare an

int
with a
BigInteger
in Java? I specifically need the know if an
int
is less than a
BigInteger
. Here is the code I am using:

private static BigInteger two = new BigInteger("2");
private static BigInteger three = new BigInteger("3");
private static BigInteger zero = new BigInteger("0");
public static BigInteger bigIntSqRootCeil(BigInteger x) throws IllegalArgumentException {
if (x.compareTo(BigInteger.ZERO) < 0) {
throw new IllegalArgumentException("Negative argument.");
}
if (x == BigInteger.ZERO || x == BigInteger.ONE) {
return x;
}
BigInteger two = BigInteger.valueOf(2L);
BigInteger y;
for (y = x.divide(two);
y.compareTo(x.divide(y)) > 0;
y = ((x.divide(y)).add(y)).divide(two));
if (x.compareTo(y.multiply(y)) == 0) {
return y;
} else {
return y.add(BigInteger.ONE);
}
}
private static boolean isPrimeBig(BigInteger n){
if (n.mod(two) == zero)
return (n.equals(two));
if (n.mod(three) == zero)
return (n.equals(three));
BigInteger m = bigIntSqRootCeil(n);
for (int i = 5; i <= m; i += 6) {
if (n.mod(BigInteger.valueOf(i)) == zero)
return false;
if(n.mod(BigInteger.valueOf(i + 2)) == zero)
return false;
};
return true;
};


Thanks.

Joe Joe
Answer

How do I compare an int with a BigInteger in Java? I specifically need the know if an int is less than a BigInteger.

Turn the int into a BigInteger before comparing:

if (BigInteger.valueOf(intValue).compareTo(bigIntegerValue) < 0) {
  // intValue is less than bigIntegerValue
}
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