Java Guava | factorial(int n) method of IntMath Class with Examples

The factorial(int n) method of Guava’s IntMath Class returns the product of the first n positive integers, which is n!.

Syntax:

public static int factorial(int n)

Parameter: The method accepts only one parameter n which is of integer type and is to be used to find the factorial.

Return Value: This method return following values:

• This method returns 1 if n is 0.
• This method returns product of the first n positive integers if the result fits in a int.
• This method returns Integer.MAX_VALUE if the result does not fit in a int.

Exceptions: The method factorial(int n) throws IllegalArgumentException if n is negative.

Example 1:

 // Java code to show implementation of // factorial(int n) method of Guava's // IntMath class    import java.math.RoundingMode; import com.google.common.math.IntMath;    class GFG {        // Driver code     public static void main(String args[])     {         int n1 = 10;            // Using factorial(int n) method of         // Guava's IntMath class         int ans1 = IntMath.factorial(n1);            System.out.println("factorial of "                            + n1 + " is : "                            + ans1);            int n2 = 12;            // Using factorial(int n) method of         // Guava's IntMath class         int ans2 = IntMath.factorial(n2);            System.out.println("factorial of "                            + n2 + " is : "                            + ans2);     } }

Output:

factorial of 10 is : 3628800
factorial of 12 is : 479001600

Example 2 :

 // Java code to show implementation of // factorial(int n) method of Guava's // IntMath class import java.math.RoundingMode; import com.google.common.math.IntMath;    class GFG {        static int findFact(int n)     {         try {                // Using factorial(int n) method of             // Guava's IntMath class             // This should throw "IllegalArgumentException"             // as n < 0             int ans = IntMath.factorial(n);                // Return the answer             return ans;         }         catch (Exception e) {             System.out.println(e);             return -1;         }     }        // Driver code     public static void main(String args[])     {         int n = -5;            try {                // Function calling             findFact(n);         }         catch (Exception e) {             System.out.println(e);         }     } }

Output:

java.lang.IllegalArgumentException: n (-5) must be >= 0

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