Prime and Pattern

src/com/sks/hkr/java/JavaPrimality.java

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+package com.sks.hkr.java;
+
+import java.util.Scanner;
+
+
+public class JavaPrimality {
+
+
+    private static final Scanner scanner = new Scanner(System.in);
+
+    public static void main(String[] args) {
+
+        /**
+         * Other approach
+
+         BigInteger bigInt=scanner.nextBigInteger();
+         System.out.println(bigInt.isProbablePrime(100) ? "prime" : "not prime");
+         scanner.close();
+         */
+
+
+        String num = scanner.nextLine();
+        int n = Integer.parseInt(num);
+        boolean flag = false;
+        for (int i = 2; i <= n / 2; i++) {
+            if (n % i == 0) {
+                flag = true;
+                break;
+            }
+        }
+        if (!flag)
+            System.out.println("prime");
+        else
+            System.out.println(" is not a prime number.");
+        scanner.close();
+    }
+
+}
+

src/com/sks/hkr/java/PatternSyntaxChecker.java

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+package com.sks.hkr.java;
+
+import java.util.Scanner;
+import java.util.regex.Pattern;
+
+public class PatternSyntaxChecker {
+
+    public static void main(String[] args) {
+        Scanner in = new Scanner(System.in);
+        int testCases = Integer.parseInt(in.nextLine());
+        while (testCases > 0) {
+            String pattern = in.nextLine();
+            //Write your code
+            try {
+                Pattern pat = Pattern.compile(pattern);
+                System.out.println("Valid");
+            } catch (Exception e) {
+                System.out.println("Invalid");
+            }
+            testCases--;
+        }
+    }
+
+
+}