Java Guava | log2(int x, RoundingMode mode) method of IntMath
The log2(int x, RoundingMode mode) method of Guava’s IntMath 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(int x, RoundingMode mode)
Parameters : The method takes 2 parameters, where x is an integer 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 :
- 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 IntMath:
Example 1 :
import java.math.RoundingMode;
import com.google.common.math.IntMath;
class GFG {
public static void main(String args[])
{
int a1 = 1542 ;
System.out.println(IntMath.log2(a1, RoundingMode.HALF_EVEN));
int a2 = 451 ;
System.out.println(IntMath.log2(a2, RoundingMode.HALF_DOWN));
}
}
|
Example 2 :
import java.math.RoundingMode;
import com.google.common.math.IntMath;
class GFG {
static int findlog2( int x, RoundingMode mode)
{
try {
int ans = IntMath.log2(x, mode);
return ans;
}
catch (Exception e) {
System.out.println(e);
return - 1 ;
}
}
public static void main(String args[])
{
int x = - 152 ;
try {
findlog2(x, RoundingMode.HALF_EVEN);
}
catch (Exception e) {
System.out.println(e);
}
}
}
|
Output:
java.lang.IllegalArgumentException: x (-152) must be > 0
Reference :
https://google.github.io/guava/releases/20.0/api/docs/com/google/common/math/IntMath.html#log2-int-java.math.RoundingMode-
Last Updated :
23 Jan, 2019
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