# Guava - IntMath Class

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.No Method & Description
1

static 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.

2

static int checkedAdd(int a, int b)

Returns the sum of a and b, provided it does not overflow.

3

static int checkedMultiply(int a, int b)

Returns the product of a and b, provided it does not overflow.

4

static int checkedPow(int b, int k)

Returns the b to the kth power, provided it does not overflow.

5

static int checkedSubtract(int a, int b)

Returns the difference of a and b, provided it does not overflow.

6

static int divide(int p, int q, RoundingMode mode)

Returns the result of dividing p by q, rounding using the specified RoundingMode.

7

static 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.

8

static int gcd(int a, int b)

Returns the greatest common divisor of a, b.

9

static boolean isPowerOfTwo(int x)

Returns true if x represents a power of two.

10

static int log10(int x, RoundingMode mode)

Returns the base-10 logarithm of x, rounded according to the specified rounding mode.

11

static int log2(int x, RoundingMode mode)

Returns the base-2 logarithm of x, rounded according to the specified rounding mode.

12

static int mean(int x, int y)

Returns the arithmetic mean of x and y, rounded towards negative infinity.

13

static int mod(int x, int m)

Returns x mod m, a non-negative value less than m.

14

static int pow(int b, int k)

Returns b to the kth power.

15

static 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;

public class GuavaTester {

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

private void testIntMath() {
try {

} 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
```
guava_math_utilities.htm