一个简单的 BitSet

public class BitSet {

/*private final static int BITS_PER_WORD = 1 << ADDRESS_BITS_PER_WORD;

public BitSet() {
initWords(BITS_PER_WORD);
}

public BitSet(int nbits) {
initWords(nbits);
}

private void initWords(int nbits) {
a = new long[wordIndex(nbits - 1) + 1];
}*/
private static long[] a =new long[640];
private final static int ADDRESS_BITS_PER_WORD = 6;
public static void main(String[] args) {
//test();
/* System.out.println(wordIndex(63));
System.out.println(wordIndex(64));
System.out.println(wordIndex(127));
System.out.println(wordIndex(128));

System.out.println("---------------");

System.out.println(63 / 64);
System.out.println(64 /64);
System.out.println(127 / 64);
System.out.println(128 / 64); */

BitSet bitSet = new BitSet();
bitSet.set(4);
// bitSet.clear(4);
System.out.println(bitSet.get(4));

}

public void clear(int bitIndex) {
//取反后在取并
//假如bitIndex =2  0010 取反=1101,并=0
a[wordIndex(bitIndex)] &= ~(1L << bitIndex);
}

public static void test(){
// BitSet
BitSet a = new BitSet();
a.set(1);

System.out.println(a.get(1));
System.out.println(a.get(2));

System.out.println("---------------------");

for (int i = 1; i < 320; i++) {
if (i < 150) {
a.set(i);
}
if (i == 150) {
System.out.println("---150-");
}
System.out.println(a.get(i));
}

}

private static int wordIndex(int bitIndex) {
return bitIndex >> ADDRESS_BITS_PER_WORD;
}

public boolean get(int bitIndex) {
//假如bitIndex=2 ; 0010 & 0010
return ((a[wordIndex(bitIndex)] & (1L << bitIndex)) != 0);
}

public void set(int bit) {
a[wordIndex(bit)] |= (1L << bit);
/*
* //0000 |= 0010 a[0] |= (1 << 1);
* System.out.println(a[0]);
* //0010 |=0100 a[0] |= (1 << 2);
* System.out.println(a[0]);
* //0010 |= 1000 a[0] |= (1 << 3);
*  System.out.println(a[0]);
*/
}

}