Returns a byte array of at least length 1 : Bitwise Operators « Operators « Java Tutorial

import java.util.BitSet;

public class Main {
  public static void main(String[] argv) throws Exception {
    BitSet bitset = new BitSet();

  public static byte[] toByteArray(BitSet bits) {
    byte[] bytes = new byte[bits.length() / 8 + 1];
    for (int i = 0; i < bits.length(); i++) {
      if (bits.get(i)) {
        bytes[bytes.length - i / 8 - 1] |= 1 << (i % 8);
    return bytes;

3.5.Bitwise Operators
3.5.1.The Bitwise Operators can be applied to the integer types, long, int, short, char, and byte.
3.5.2.The Bitwise Logical Operators
3.5.3.Bitwise AND (&)
3.5.4.Bitwise OR (|)
3.5.5.Bitwise XOR (^)
3.5.6.Left shift (<<)
3.5.7.Bitwise complement (~): inverts ones and zeros in a number
3.5.8.Demonstrate the bitwise logical operators
3.5.9.All bitwise operators in action
3.5.10.Bitwise Operator Assignments
3.5.11.The Left Shift
3.5.12.Left shifting as a quick way to multiply by 2
3.5.13.The Right Shift
3.5.14.The Unsigned Right Shift
3.5.15.Signed shift to the right
3.5.16.Unsigned shifting a byte value.
3.5.17.Convert a number to negative and back
3.5.18.Performing Bitwise Operations on a Bit Vector
3.5.19.Converting Between a BitSet and a Byte Array
3.5.20.Returns a byte array of at least length 1
3.5.21.Use bitwise operator to create hash code
3.5.22.Operations on bit-mapped fields.
3.5.23.Represents a collection of 64 boolean (on/off) flags.