JAVA版位图排序（算法珠玑开篇的例子）

package com.sdo.tradinghub.domain; public class BitSortTest { private static final int BITSPERWORD = 32; // 整数位数 private static final int SHIFT = 5; private static final int MASK = 0x1F; // 5位遮蔽 0B11111 private static final int N = 10000000; // 用int数组来模拟位数组，总计(1 + N / BITSPERWORD)*BITSPERWORD位，足以容纳N private static int[] a = new int[(1 + N / BITSPERWORD)]; public static void main(String[] args) { bitsort(new int[] { 1, 100, 2, 10000, 9999, 4567, 78902 }); } public static void bitsort(int[] array) { for (int i = 0; i < N; i++) clr(i); // 位数组所有位清0 for (int i = 0; i < array.length; i++) set(array[i]); // 阶段2 for (int i = 0; i < N; i++) if (test(i)) System.out.println(i); } // 置a[i>>SHIFT]的第(i & MASK)位为1，也就是位数组的第i位为1 public static void set(int i) { a[i >> SHIFT] |= (1 << (i & MASK)); } // 置a[i>>SHIFT]的第(i & MASK)位为0,也就是位数组的第i位为0 public static void clr(int i) { a[i >> SHIFT] &= ~(1 << (i & MASK)); } // 测试位数组的第i位是否为1 public static boolean test(int i) { return (a[i >> SHIFT] & (1 << (i & MASK))) == (1 << (i & MASK)); } }