上溢到最近的2^n

        int newCapacity = 1;
        newCapacity |= newCapacity >>>  1;
        newCapacity |= newCapacity >>>  2;
        newCapacity |= newCapacity >>>  4;
        newCapacity |= newCapacity >>>  8;
        newCapacity |= newCapacity >>> 16;
        newCapacity ++;

 

 

以上代码只是把数字变成0000011的形式，++后变成0000000100