Java floor floorLogBaseTwo(final int i)

Description

Returns the log base 2 of an integer, rounded to the floor.

License

Open Source License

Parameter

Parameter	Description
i	The integer

Exception

Parameter	Description
IllegalArgumentException	if the integer passed in is zero or negative.

Return

int the log base 2 of an integer, rounded to the floor.

Declaration

public static int floorLogBaseTwo(final int i) 

Method Source Code

//package com.java2s;
/*//from  w  ww. j  a va  2 s.c  o  m
 * Copyright Matt Palmer 2009-2014, All rights reserved.
 *
 * This code is licensed under a standard 3-clause BSD license:
 * 
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 *  * Redistributions of source code must retain the above copyright notice, 
 *    this list of conditions and the following disclaimer.
 * 
 *  * Redistributions in binary form must reproduce the above copyright notice, 
 *    this list of conditions and the following disclaimer in the documentation 
 *    and/or other materials provided with the distribution.
 * 
 *  * The names of its contributors may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE 
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
 * POSSIBILITY OF SUCH DAMAGE.
 */

public class Main {
    /**
     * Returns the log base 2 of an integer, rounded to the floor.
     * 
     * Note that the integer must be positive.
     * 
     * @param i The integer
     * @return int the log base 2 of an integer, rounded to the floor. 
     * @throws IllegalArgumentException if the integer passed in is zero or negative.
     */
    public static int floorLogBaseTwo(final int i) {
        checkPositiveInteger(i);
        return 31 - Integer.numberOfLeadingZeros(i);
    }

    private static void checkPositiveInteger(final int value) {
        if (value <= 0) {
            throw new IllegalArgumentException("The value must be positive " + value);
        }
    }
}

Related

1. floorDivide(long numerator, long denominator)
2. floorDivision(int i, int divisor)
3. floorHalf(int num)
4. floorInt(Double d, double intv)
5. floorInt(float x)
6. floorLong(final double x)
7. floormod(float a, float b)
8. floorMod(long x, long y)
9. floorMod(long x, long y)