Is it possible to shift a Java BitSet using the logical operators?

Question

For example I have a BitSet BitSet x = new BitSet(32); and I set bit 3 x.set(2, true);
Is there anyways to do a logical shift like x << someAmount; that pads with 0's?

Answer 1

Here is how you would shift them right and left 8 bits.

BitSet bits = new BitSet();
bits.set(10);
bits.set(30);
System.out.println("unshifted:" + bits);
System.out.println("right shift: " + shift(bits, 8));
System.out.println("left shift: " + shift(bits,-8));

Prints

unshifted: {10, 30}
right shift: {18, 38}
left shift: {2, 22}

Here is the method

• it streams the current positions
• and adjusts them based on the shift amount.
• Positions due to negative shifts are dropped as they would be out of range.
• the new BitSet is returned.

    
public static BitSet shift(BitSet bitset, int shiftAmount) {
    BitSet b = new BitSet();
    bitset.stream().map(bitPos -> bitPos + shiftAmount)
            .dropWhile(bitPos -> bitPos < 0)
            .forEach(bitPos -> b.set(bitPos));
    return b;
}

Note the a BitSet is oriented starting with 1,2,4,8 which is opposite of a normal binary number. Also note that in the above left shifted bits will lose trailing zeros. Right shifted will gain padded ones on the left.