Java Bit Count countBits(long num)

Description

count 1 bits in nubmer.

License

Open Source License

Parameter

Parameter	Description
num	number to count bits in it.

Return

number of 1 bits.

Declaration

public static byte countBits(long num) 

Method Source Code

//package com.java2s;
//License from project: Open Source License 

public class Main {
    /**/* ww w  .  j a  v  a2  s  . c om*/
     * count 1 bits in nubmer.
     * <p>
     * {@literal 10: 1010 -> 2}<br>
     * {@literal 2: 10 -> 1}<br>
     * {@literal 56: 111000 -> 3}<br>
     * {@literal 34: 100010 -> 2}<br>
     * {@literal 255: 11111111 -> 8}<br>
     * {@literal 256: 100000000 -> 1}<br>
     *
     * @param num number to count bits in it.
     *
     * @return number of 1 bits.
     */
    public static byte countBits(long num) {
        byte result;
        for (result = 0; Math.abs(num) > 0; result++) {
            num &= num - 1;
        }
        return result;
    }

    /**
     * count 1 bits in nubmer.
     * <p>
     * {@literal 10: 1010 -> 2}<br>
     * {@literal 2: 10 -> 1}<br>
     * {@literal 56: 111000 -> 3}<br>
     * {@literal 34: 100010 -> 2}<br>
     * {@literal 255: 11111111 -> 8}<br>
     * {@literal 256: 100000000 -> 1}<br>
     *
     * @param num number to count bits in it.
     *
     * @return number of 1 bits.
     */
    public static byte countBits(int num) {
        byte result;
        for (result = 0; Math.abs(num) > 0; result++) {
            num &= num - 1;
        }
        return result;
    }

    /**
     * count 1 bits in nubmer.
     * <p>
     * {@literal 10: 1010 -> 2}<br>
     * {@literal 2: 10 -> 1}<br>
     * {@literal 56: 111000 -> 3}<br>
     * {@literal 34: 100010 -> 2}<br>
     * {@literal 255: 11111111 -> 8}<br>
     * {@literal 256: 100000000 -> 1}<br>
     *
     * @param num number to count bits in it.
     *
     * @return number of 1 bits.
     */
    public static byte countBits(short num) {
        byte result;
        for (result = 0; num > 0; result++) {
            num &= num - 1;
        }
        return result;
    }

    /**
     * count 1 bits in nubmer.
     * <p>
     * {@literal 10: 1010 -> 2}<br>
     * {@literal 2: 10 -> 1}<br>
     * {@literal 56: 111000 -> 3}<br>
     * {@literal 34: 100010 -> 2}<br>
     * {@literal 255: 11111111 -> 8}<br>
     * {@literal 256: 100000000 -> 1}<br>
     *
     * @param num number to count bits in it.
     *
     * @return number of 1 bits.
     */
    public static byte countBits(char num) {
        byte result;
        for (result = 0; num > 0; result++) {
            num &= num - 1;
        }
        return result;
    }

    /**
     * count 1 bits in nubmer.
     * <p>
     * {@literal 10: 1010 -> 2}<br>
     * {@literal 2: 10 -> 1}<br>
     * {@literal 56: 111000 -> 3}<br>
     * {@literal 34: 100010 -> 2}<br>
     * {@literal 255: 11111111 -> 8}<br>
     * {@literal 256: 100000000 -> 1}<br>
     *
     * @param num number to count bits in it.
     *
     * @return number of 1 bits.
     */
    public static byte countBits(byte num) {
        byte result;
        for (result = 0; num > 0; result++) {
            num &= num - 1;
        }
        return result;
    }
}

Related

1. countBits(int i)
2. countBits(int mask)
3. countBits(int n)
4. countBits(int x)
5. countBits(int x)
6. countBits(long value)
7. countBitsInMask(int mask)
8. countBitsNeeded(int value)
9. countBitsSet(int bitfield)