Java Guava | LongMath.checkedMultiply(int a, int b) method with Examples

The checkedMultiply(long a, long b) is a method of Guava’s LongMath Class which accepts two parameters a and b, and returns their product.

Syntax:

public static long checkedMultiply(long a, long b)

Parameters: The method accepts two long values a and b and computes their product.

Return Value: The method returns the product of long values passed to it, provided it does not overflow.

Exceptions: The method checkedMultiply(long a, long b) throws ArithmeticException if the product i.e, (a – b) overflows in signed long arithmetic.

Below examples illustrate the implementation of above method:

Example 1:

// Java code to show implementation of
// checkedMultiply(long a, long b) method
// of Guava's LongMath class

import java.math.RoundingMode;
import com.google.common.math.LongMath;

class GFG {

    // Driver code
    public static void main(String args[])
    {
        long a1 = 25;
        long b1 = 36;

        // Using checkedMultiply(long a, long b)
        // method of Guava's LongMath class
        long ans1 = LongMath.checkedMultiply(a1, b1);

        System.out.println("Product of " + a1 + " and "
                           + b1 + " is: " + ans1);

        long a2 = 150;
        long b2 = 667;

        // Using checkedMultiply(long a, long b)
        // method of Guava's LongMath class
        long ans2 = LongMath.checkedMultiply(a2, b2);

        System.out.println("Product of " + a2 + " and "
                           + b2 + " is: " + ans2);
    }
}

Output:

Product of 25 and 36 is: 900
Product of 150 and 667 is: 100050

Example 2:

// Java code to show implementation of
// checkedMultiply(long a, long b) method
// of Guava's LongMath class

import java.math.RoundingMode;
import com.google.common.math.LongMath;

class GFG {

    static long findDiff(long a, long b)
    {
        try {

            // Using checkedMultiply(long a, long b) method
            // of Guava's LongMath class
            // This should throw "ArithmeticException"
            // as the product overflows in signed
            // long arithmetic
            long ans = LongMath.checkedMultiply(a, b);

            // Return the answer
            return ans;
        }
        catch (Exception e) {
            System.out.println(e);
            return -1;
        }
    }

    // Driver code
    public static void main(String args[])
    {
        long a = Long.MIN_VALUE;
        long b = 452;

        try {

            // Function calling
            findDiff(a, b);
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

Output:

java.lang.ArithmeticException: overflow

Reference :
https://google.github.io/guava/releases/20.0/api/docs/com/google/common/math/LongMath.html#checkedMultiply-long-long-