Merge pull request #49 from Sreenivasulu-03/feature/PrimeCheck

Added Prime number Checker in Java

Author: IamBisrutPyne

snippets/Algorithms/java/PrimeNumberCheck.java

@@ -0,0 +1,57 @@
+import java.util.Scanner;
+
+/**
+ * Program Title: Prime Number Checker
+ * Author: [Sreenivasulu-03]
+ * Date: 2025-10-08
+ *
+ * Description: This program checks whether a given number is a prime number or not.
+ * A prime number is a number greater than 1 that has no positive divisors other than
+ * 1 and itself. The program uses an efficient method by checking divisibility only up to √n.
+ *
+ * Time Complexity: O(√n)
+ * Space Complexity: O(1)
+ */
+
+public class PrimeNumberCheck {
+
+    /**
+     * Checks if a number is prime.
+     * @param n The number to check.
+     * @return true if n is prime, false otherwise.
+     */
+    public static boolean isPrime(int n) {
+        if (n <= 1) return false;
+        if (n == 2) return true;
+        if (n % 2 == 0) return false;
+
+        // Check divisibility from 3 to √n
+        for (int i = 3; i * i <= n; i += 2) {
+            if (n % i == 0) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    public static void main(String[] args) {
+        try (Scanner sc = new Scanner(System.in)) {
+            System.out.print("Enter a number: ");
+
+            while (!sc.hasNextInt()) {
+                System.out.print("Invalid input! Please enter a valid number: ");
+                sc.next();
+            }
+
+            int number = sc.nextInt();
+
+            if (isPrime(number)) {
+                System.out.println(number + " is a prime number.");
+            } else {
+                System.out.println(number + " is not a prime number.");
+            }
+        } catch (Exception e) {
+            System.err.println("An unexpected error occurred: " + e.getMessage());
+        }
+    }
+}