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Guava – IntMath Class

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IntMath

IntMath provides utility methods on int.

Class Declaration

Following is the declaration for com.google.common.math.IntMath class −

@GwtCompatible(emulated = true)
public final class IntMath
   extends Object

Methods

Sr.NoMethod & Description
1static int binomial(int n, int k)Returns n choose k, also known as the binomial coefficient of n and k, or Integer.MAX_VALUE if the result does not fit in an int.
2static int checkedAdd(int a, int b)Returns the sum of a and b, provided it does not overflow.
3static int checkedMultiply(int a, int b)Returns the product of a and b, provided it does not overflow.
4static int checkedPow(int b, int k)Returns the b to the kth power, provided it does not overflow.
5static int checkedSubtract(int a, int b)Returns the difference of a and b, provided it does not overflow.
6static int divide(int p, int q, RoundingMode mode)Returns the result of dividing p by q, rounding using the specified RoundingMode.
7static int factorial(int n)Returns n!, that is, the product of the first n positive integers, 1 if n == 0, or Integer.MAX_VALUE if the result does not fit in a int.
8static int gcd(int a, int b)Returns the greatest common divisor of a, b.
9static boolean isPowerOfTwo(int x)Returns true if x represents a power of two.
10static int log10(int x, RoundingMode mode)Returns the base-10 logarithm of x, rounded according to the specified rounding mode.
11static int log2(int x, RoundingMode mode)Returns the base-2 logarithm of x, rounded according to the specified rounding mode.
12static int mean(int x, int y)Returns the arithmetic mean of x and y, rounded towards negative infinity.
13static int mod(int x, int m)Returns x mod m, a non-negative value less than m.
14static int pow(int b, int k)Returns b to the kth power.
15static int sqrt(int x, RoundingMode mode)Returns the square root of x, rounded with the specified rounding mode.

Methods Inherited

This class inherits methods from the following class −

  • java.lang.Object

Example of IntMath Class

Create the following java program using any editor of your choice in say C:/> Guava.

GuavaTester.java

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

public class GuavaTester {

   public static void main(String args[]) {
      GuavaTester tester = new GuavaTester();
      tester.testIntMath();
   }

   private void testIntMath() {
      try {
         System.out.println(IntMath.checkedAdd(Integer.MAX_VALUE, Integer.MAX_VALUE));
         
      } catch(ArithmeticException e) {
         System.out.println("Error: " + e.getMessage());
      }

      System.out.println(IntMath.divide(100, 5, RoundingMode.UNNECESSARY));
      try {
         //exception will be thrown as 100 is not completely divisible by 3
         // thus rounding is required, and RoundingMode is set as UNNESSARY
         System.out.println(IntMath.divide(100, 3, RoundingMode.UNNECESSARY));
         
      } catch(ArithmeticException e) {
         System.out.println("Error: " + e.getMessage());
      }

      System.out.println("Log2(2): " + IntMath.log2(2, RoundingMode.HALF_EVEN));

      System.out.println("Log10(10): " + IntMath.log10(10, RoundingMode.HALF_EVEN));

      System.out.println("sqrt(100): " + IntMath.sqrt(IntMath.pow(10,2), RoundingMode.HALF_EVEN));

      System.out.println("gcd(100,50): " + IntMath.gcd(100,50));

      System.out.println("modulus(100,50): " + IntMath.mod(100,50));

      System.out.println("factorial(5): " + IntMath.factorial(5));
   }
}

Verify the Result

Compile the class using javac compiler as follows −

C:\Guava>javac GuavaTester.java

Now run the GuavaTester to see the result.

C:\Guava>java GuavaTester

See the result.

Error: overflow
20
Error: mode was UNNECESSARY, but rounding was necessary
Log2(2): 1
Log10(10): 1
sqrt(100): 10
gcd(100,50): 50
modulus(100,50): 0
factorial(5): 120

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