sample for BAEL-747 Check if a number is prime in Java (#1508)

core-java/src/main/java/com/baeldung/primechecker/BigIntegerPrimeChecker.java

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+package com.baeldung.primechecker;
+
+import java.math.BigInteger;
+
+public class BigIntegerPrimeChecker implements PrimeChecker{
+
+    @Override
+    public boolean isPrime(int number) {
+        BigInteger bigInt = BigInteger.valueOf(number);
+        return bigInt.isProbablePrime(100);
+    }
+
+}

core-java/src/main/java/com/baeldung/primechecker/BruteForcePrimeChecker.java

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+package com.baeldung.primechecker;
+
+import java.util.stream.IntStream;
+
+public class BruteForcePrimeChecker implements PrimeChecker{
+
+    @Override
+    public boolean isPrime(int number) {
+        return IntStream.range(2, number).filter(n -> (number % n == 0)).count() == 0;
+    }
+
+    
+}       

core-java/src/main/java/com/baeldung/primechecker/OptimisedPrimeChecker.java

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+package com.baeldung.primechecker;
+
+import java.util.stream.IntStream;
+
+public class OptimisedPrimeChecker implements PrimeChecker{
+
+    @Override
+    public boolean isPrime(int number) {
+        return IntStream.range(2, (int)Math.sqrt(number) + 1)
+            .filter(n -> (number % n == 0))
+            .count() == 0;
+    }
+
+    
+}

core-java/src/main/java/com/baeldung/primechecker/PrimeChecker.java

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+package com.baeldung.primechecker;
+
+public interface PrimeChecker {
+    
+    public boolean isPrime( int number );
+}

core-java/src/main/java/com/baeldung/primechecker/PrimesPrimeChecker.java

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+package com.baeldung.primechecker;
+
+import org.apache.commons.math3.primes.Primes;
+
+public class PrimesPrimeChecker implements PrimeChecker{
+
+    @Override
+    public boolean isPrime(int number) {
+        return Primes.isPrime(number);
+    }
+
+}