Java Guava | ceilingPowerOfTwo() method of IntMath Class

The ceilingPowerOfTwo(int x) method of Guava’s IntMath class accepts a parameter and calculates the smallest power of two greater than the values passed in the parameter. This method is equivalent to checkedPow(2, log2(x, CEILING)).

Syntax :

public static int ceilingPowerOfTwo(int x)

Parameter: This method accepts a single parameter x which is of integer type and returns the smallest power of two greater than the values passed in the parameter.

Return Value : Smallest power of two greater than or equal to x.

Exceptions :

• IllegalArgumentException : This method throws an IllegalArgumentException if x <= 0.
• ArithmeticException: This method throws an ArithmeticException if the next-higher power of two is not representable as an int, i.e. when x > 2^30.

Below examples illustrate the ceilingPowerOfTwo() method of IntMath class:

Example 1 :

// Java code to show implementation of
// isPrime(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 a1 = 63;

        // Using isPrime(int n)
        // method of Guava's IntMath class
        if(IntMath.isPrime(a1))
        System.out.println(a1 + " is a prime number");
        else
        System.out.println(a1 + " is not a prime number");

        int a2 = 17;

        // Using isPrime(int n)
        // method of Guava's IntMath class
        if(IntMath.isPrime(a2))
        System.out.println(a2 + " is a prime number");
        else
        System.out.println(a2 + " is not a prime number");
    }
}

Output :

Smallest power of 2 greater than or equal to 25 is : 32
Smallest power of 2 greater than or equal to 65 is : 128

Example 2 :

// Java code to show implementation of
// ceilingPowerOfTwo(int x) method of Guava's
// IntMath class
import java.math.RoundingMode;
import com.google.common.math.IntMath;

class GFG {

    static int findCeilPow(int x)
    {
        try {

            // Using ceilingPowerOfTwo(int x)
            // method of Guava's IntMath class
            // This should throw "IllegalArgumentException"
            // as x <= 0
            int ans = IntMath.ceilingPowerOfTwo(x);

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

    // Driver code
    public static void main(String args[])
    {
        int n = -4;

        try {
            // Function calling
            findCeilPow(n);;
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

Output :

java.lang.IllegalArgumentException: x (-4) must be > 0

Reference :
https://google.github.io/guava/releases/20.0/api/docs/com/google/common/math/IntMath.html#ceilingPowerOfTwo-int-