转自菜鸟教程。
一个Bitset类创建一种特殊类型的数组来保存位置。Bitset中数组大小会随需要增加。这和位向量（vector of bits）比较类似。这是一个传统的类，但它在Java 2中完全重新设计。
Bitset两个构造方法。

BitSet()	     //创建一个默认的对象

BitSet(int size) //指定初始大小，所有位初始化为0

BitSet常用方法

import java.util.BitSet;
 
public class BitSetDemo {
 
  public static void main(String args[]) {
         BitSet bits1 = new BitSet(16);
	     BitSet bits2 = new BitSet(16);
	      
	     // set some bits
	     for(int i=0; i<16; i++) {
	        if((i%2) == 0) bits1.set(i);
	        if((i%6) != 0) bits2.set(i);
	     }
	     System.out.println("Initial pattern in bits1: ");
	     System.out.println(bits1);
	     System.out.println("\nInitial pattern in bits2: ");
	     System.out.println(bits2);

	     // AND bits
	     bits2.and(bits1);
	     System.out.println("\nbits2 AND bits1: ");
	     System.out.println(bits2);

	     // OR bits
	     bits2.or(bits1);
	     System.out.println("\nbits2 OR bits1: ");
	     System.out.println(bits2);

		 // XOR bits
	     bits2.xor(bits1);
	     System.out.println("\nbits2 XOR bits1: ");
	     System.out.println(bits2);
  }

}

运行结果

Initial pattern in bits1: 
{0, 2, 4, 6, 8, 10, 12, 14}		////这些数字表示第几位为1

Initial pattern in bits2: 
{1, 2, 3, 4, 5, 7, 8, 9, 10, 11, 13, 14, 15}

bits2 AND bits1: 
{2, 4, 8, 10, 14}

bits2 OR bits1: 	//bits2:{2, 4, 8, 10, 14}  or  bits1:{0, 2, 4, 6, 8, 10, 12, 14}
{0, 2, 4, 6, 8, 10, 12, 14}

bits2 XOR bits1: 	//bits2:{0, 2, 4, 6, 8, 10, 12, 14}  or  bits1:{0, 2, 4, 6, 8, 10, 12, 14}
{}