Added Factorial Program.

Author: iamarav

Basic-Java/Factorial.java

@@ -0,0 +1,51 @@
+import java.util.Scanner;
+
+public class Factorial {
+
+	public static void main(String[] args) {
+
+		System.out.println("Program to find factorial of a number\n---");
+
+		int num;
+		Scanner scanner = new Scanner (System.in);
+		
+		System.out.print("Enter the number: ");
+		num = scanner.nextInt();
+		
+		if (num>20 || num< -20) {
+			System.out.println("Cannot perform factorial for input greater than or lesser than 20.");
+			end();
+		}
+		scanner.close();
+		
+		if (num<0) {
+			num = -num;
+			System.out.println("-"+num+"! = -"+factorial(num));
+			end();
+			//For numbers lesser than zero.
+		}
+		else {
+			System.out.println(num+"! = "+factorial(num));
+			end();
+			//For numbers greater than or equal to zero.
+		}
+		
+	}
+
+	private static long factorial(int num) {
+		
+		long n = num, output = 1;
+		
+		while (n>0) {
+			output = output*n;
+			n-=1;
+		}
+		return output;
+	}
+
+	private static void end() {
+		System.out.println("---\nThe Program has ended.");
+		System.exit(0);
+	}
+	
+}

README.md

@@ -25,6 +25,7 @@ ___
 | 9     | [Prime Number Checker](/Basic-Java/PrimeNumberChecker.java)  | A Program to check if the entered number is a Prime Number or not. | if/else, for loops     |
 | 10    | [ASCII Value Of Character](/Basic-Java/AsciiOfCharacter.java) | A Program to find ASCII Value of a Character entered.        | TypeCasting            |
 | 11    | [Generate Random Number](/Basic-Java/RandomNumberGeneration.java) | A Program to generate Random Number, Also to generate Random Number between a Range. | Math.random() function |
+| 12    | [Factorial](/Basic-Java/Factorial.java)                      | A Program to find Factorial of an Integer.                   | while loop             |
 
 ### List of Other Programs: