标签：arraylist lap sed 去重 alt pac 检查 void mem
package com.zsins.risk.util; import java.io.Serializable; public class LongMap implements BitMap, Serializable { private static final long serialVersionUID = 1L; private final long[] longs; /** * 构造 */ public LongMap() { longs = new long[93750000]; } /** * 构造 * * @param size 容量 */ public LongMap(int size) { longs = new long[size]; } @Override public void add(long i) { int r = (int) (i / BitMap.MACHINE128); long c = i % BitMap.MACHINE128; longs[r] = longs[r] | (1L << c); } @Override public boolean contains(long i) { int r = (int) (i / BitMap.MACHINE128); long c = i % BitMap.MACHINE128; return ((longs[r] >>> c) & 1) == 1; } @Override public void remove(long i) { int r = (int) (i / BitMap.MACHINE128); long c = i % BitMap.MACHINE128; longs[r] &= ~(1L << c); } }
package com.zsins.risk.util; /** * BitMap接口，用于将某个int或long值映射到一个数组中，从而判定某个值是否存在 * * @author looly * */ public interface BitMap{ int MACHINE32 = 32; int MACHINE64 = 64; int MACHINE128 = 128; /** * 加入值 * * @param i 值 */ void add(long i); /** * 检查是否包含值 * * @param i 值 * @return 是否包含 */ boolean contains(long i); /** * 移除值 * * @param i 值 */ void remove(long i); }
public static void main(String[] args) {
try {
//第一种：借助BitMap,LongMap；位图去重
//存在局限性：这个方法只适合long类型；
System.out.println("----------1:"+System.currentTimeMillis());
BitMap bitMap = new LongMap();
for(long i = 0 ;i<1000000L;i++){
bitMap.add(i);
}
System.out.println("----------2:"+System.currentTimeMillis());
for(long j = 0 ;j<1000000L;j++){
bitMap.contains(j);
if(j < 10){
System.out.println("----------3:"+bitMap.contains(j));
}
}
//第二种：Set<Strig>方法去重；效率同样很快
/*
final Set<String> des = new HashSet<String>();
final List<String> sourse = new ArrayList<String>();
for(int i=0;i<1000000;i++){
des.add("10000000000"+i);
if(i<10000){
sourse.add("10000000000"+i);
}else{
sourse.add("20000000000"+i);
}
}
if (sourse == null || sourse.size() <= 0) {
return;
}
System.out.println("------111:"+sourse.size());
System.out.println("----------1:"+System.currentTimeMillis());
Iterator<String> listStr = sourse.iterator();
while (listStr.hasNext()) {
String item = listStr.next();
if (des.contains(item)) {
listStr.remove();
}
}
System.out.println("------222:"+sourse.size());
System.out.println("----------3:"+System.currentTimeMillis());*/
} catch (Exception e) {
System.out.println(e.getStackTrace());
// TODO: handle exception
System.out.println(e);
}
}
标签：arraylist lap sed 去重 alt pac 检查 void mem
原文地址：https://www.cnblogs.com/hmhhz/p/13366248.html
