java - BitSet Flip() 会影响 BitSet 的长度吗？

Question

在下面的函数中，我想根据突变概率来突变 BitSet。

public static Cell mutate(Cell original_){

    Double mProb = 0.2;

    BitSet original = new BitSet(original_.getChrom().size());

    original = (BitSet) original_.getChrom().clone();

    Random rand = new Random();
    System.out.print(" " + original.length() + " "); //to check the length of original before applying flip()

    for(int m = 0; m < original.length(); m++)
    {

        if(rand.nextDouble() <= mProb){
            original.flip(m);
        }

    }

    System.out.print(" " + original.length() + " "); //to check the length of original after applying flip()

    Cell mutated = new Cell(original);
    //System.out.print("{" + mutated.getFitness() + "} ");

    return mutated;
}

我注意到的问题是，有时 BitSet 的长度在翻转一些位后会减少!!

以下一些结果来说明问题:

original before flip || length before flip || original after flip || length after flip
110111               || 6                  || 110111              || 6
101111               || 6                  || 111                 || 3
110111               || 6                  || 10111               || 5
110111               || 6                  || 111111              || 6
111010               || 6                  || 11010               || 5

可以看到，翻转后第一个和第四个并没有减少。而其他的都减少了。我试图理解是什么导致了这个问题，但我做不到。我所需要的只是翻转后位集的长度应与翻转前原始位集的长度相同。

Answer 1

Does BitSet flip() affect the length of BitSet?

是

Javadoc对于 BitSet::length 说:

public int length()
Returns the "logical size" of this BitSet: the index of the highest set bit in the BitSet plus one. Returns zero if the BitSet contains no set bits.

BitSet b = new BitSet();
System.out.println(b.length()); // 0
b.flip(1);
System.out.println(b.length()); // 2
b.flip(1);
System.out.println(b.length()); // 0