The method log10(long x, RoundingMode mode) of Guava’s LongMath Class accepts two parameters and calculates the base-10 logarithmic value of the first parameter rounded according to the rounding mode specified by the second parameter.
Syntax:
public static int log10(long x, RoundingMode mode)
Parameters: The method takes 2 parameters:
- x is the long value to be found log of.
- mode is the specified rounding mode.
Return Value: This method returns Base-10 logarithm of x, rounded according to the specified rounding mode.
Exceptions: This method throws following parameters:
- IllegalArgumentException: if the value x is 0 or a negative value.
- ArithmeticException: if mode is RoundingMode.UNNECESSARY and x is not a power of ten.
Enum RoundingMode
| Enum Constant | Description |
|---|---|
| CEILING | Rounding mode to round towards positive infinity. |
| DOWN | Rounding mode to round towards zero. |
| FLOOR | Rounding mode to round towards negative infinity. |
| HALF_DOWN | Rounding mode to round towards “nearest neighbor” unless both neighbors are equidistant, in which case round down. |
| HALF_EVEN | Rounding mode to round towards the “nearest neighbor” unless both neighbors are equidistant, in which case, round towards the even neighbor. |
| HALF_UP | Rounding mode to round towards “nearest neighbor” unless both neighbors are equidistant, in which case round up. |
| UNNECESSARY | Rounding mode to assert that the requested operation has an exact result, hence no rounding is necessary. |
| UP | Rounding mode to round away from zero. |
Below given are some examples to understand the implementation in a better way:
Example 1:
// Java code to show implementation of// log10(long x, RoundingMode mode) 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 = 10000; // Using log10(long x, RoundingMode mode) // method of Guava's LongMath class // The RoundingMode HALF_EVEN rounds towards // the "nearest neighbor" unless both neighbors // are equidistant, in which case, round towards // the even neighbor. System.out.println( LongMath.log10( a1, RoundingMode.HALF_EVEN)); long a2 = 15; // Using log10(long x, RoundingMode mode) // method of Guava's LongMath class // The RoundingMode HALF_DOWN rounds towards // "nearest neighbor" unless both neighbors // are equidistant, in which case round down. System.out.println( LongMath.log10(a2, RoundingMode.HALF_DOWN)); }} |
Output :
4 1
Example 2 :
// Java code to show implementation of// log10(long x, RoundingMode mode) method// of Guava's LongMath class import java.math.RoundingMode;import com.google.common.math.LongMath; class GFG { static int findlog10(long x, RoundingMode mode) { try { // Using log10(long x, RoundingMode mode) // method of Guava's LongMath class // The RoundingMode HALF_EVEN rounds towards // the "nearest neighbor" unless both neighbors // are equidistant, in which case, round towards // the even neighbor. // This should throw "IllegalArgumentException" // as x <= 0 int ans = LongMath.log10(x, mode); // Return the answer return ans; } catch (Exception e) { System.out.println(e); return -1; } } // Driver code public static void main(String args[]) { long x = -122; try { // Function calling findlog10(x, RoundingMode.HALF_EVEN); } catch (Exception e) { System.out.println(e); } }} |
Output :
java.lang.IllegalArgumentException: x (-122) must be > 0
