Java Guava | log2(long x, RoundingMode mode) of LongMath Class with Examples
Last Updated :
28 Jan, 2019
The method log2(long x, RoundingMode mode) of Guava’s LongMath Class accepts two parameters and calculates the base-2 logarithmic value of the first parameter rounded according to the rounding mode specified by the second parameter.
Syntax:
public static int log2(long x, RoundingMode mode)
Parameters: The method takes 2 parameters, where x is a long and mode is a specified rounding mode.
Return Value: This method returns Base-2 logarithm of x, rounded according to the specified rounding mode.
Exceptions: This method throws following parameters:
- IllegalArgumentException: if x <= 0.
- ArithmeticException: if mode is RoundingMode.UNNECESSARY and x is not a power of two.
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 examples illustrate the implementation of log2() method of Guava LongMath:
Example 1 :
import java.math.RoundingMode;
import com.google.common.math.LongMath;
class GFG {
public static void main(String args[])
{
long n1 = 1111 ;
System.out.println(LongMath.log2(
n1,
RoundingMode.HALF_EVEN));
long n2 = 205 ;
System.out.println(LongMath.log2(
n2,
RoundingMode.HALF_DOWN));
}
}
|
Example 2:
import java.math.RoundingMode;
import com.google.common.math.LongMath;
class GFG {
static long findlog2( long x, RoundingMode mode)
{
try {
long ans = LongMath.log2(x, mode);
return ans;
}
catch (Exception e) {
System.out.println(e);
return - 1 ;
}
}
public static void main(String args[])
{
long x = - 122 ;
try {
findlog2(x, RoundingMode.HALF_EVEN);
}
catch (Exception e) {
System.out.println(e);
}
}
}
|
Output:
java.lang.IllegalArgumentException: x (-122) must be > 0
Reference: https://google.github.io/guava/releases/20.0/api/docs/com/google/common/math/LongMath.html#log2-long-java.math.RoundingMode-
Like Article
Suggest improvement
Share your thoughts in the comments
Please Login to comment...