返回在指定的起始索引上或之后出现的设置为true的第一位的索引。

//package com.nowjava;
/**
 * 时 代 J a v a - N o w J a v a . c o m 提 供 
**/


public class Main {

    public static void main(String[] argv) throws Exception {

        int bitset = 2;

        int fromIndex = 2;

        System.out.println(nextSetBit(bitset, fromIndex));

    }


    /** maximum index of a bitset (minimum index is 0) */

    public static final int MAX_INDEX = 31;
    /* 
    *来 自
     时代Java公众号 - nowjava.com
    */

    /** int with all bits set */

    public static final int INT_MASK = 0xffffffff;


    /**

     * Returns the index of the first bit that is set to <code>true</code> that

     * occurs on or after the specified starting index. If no such bit exists

     * then -1 is returned.

     * 

     * To iterate over the <code>true</code> bits in a bitset, use the following

     * loop:

     * 

     * <pre>

     * for (int i = nextSetBit(bitset, 0); i &gt;= 0; i = nextSetBit(bitset, i + 1))

     *     ; // do something

     * </pre>

     * 

     * @param  bitset

     *         a bitset.

     * @param  fromIndex

     *         the bit index after which the first bit that is set to

     *         <code>true</code> is returned.

     * @return the index of the first bit that is set to <code>true</code> that

     *         occurs on or after the specified starting index

     * @throws IndexOutOfBoundsException

     *         if the specified index is negative

     */

    public static int nextSetBit(int bitset, int fromIndex)

            throws IndexOutOfBoundsException {

        checkIndexRange(fromIndex, Integer.MAX_VALUE);

        if (fromIndex > MAX_INDEX)

            return -1;

        bitset &= (INT_MASK << fromIndex);

        if (bitset != 0)

            return Integer.numberOfTrailingZeros(bitset);

        return -1;

    }


    /**

     * Throws an {@link IndexOutOfBoundsException} if the given bit index is

     * negative or if it the second argument is <code>true</code> also if the

     * index is greater than {@link #MAX_INDEX}.

     * 

     * @param  index

     * @param  checkMax

     * @throws IndexOutOfBoundsException

     */