scouter.util.TopN Maven / Gradle / Ivy
/*
* Copyright 2015 the original author or authors.
* @https://github.com/scouter-project/scouter
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package scouter.util;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Random;
public class TopN> {
private LinkedList list = new LinkedList();
private int topN;
public enum DIRECTION {
ASC,
DESC
}
private DIRECTION direction = DIRECTION.ASC;
public TopN(int max) {
this.topN = max;
}
public TopN(int max, DIRECTION direction) {
this.topN = max;
this.direction = direction;
}
public void add(V k) {
if (list.size() == 0) {
list.add(k);
return;
}
int high = list.size() - 1;
int low = 0;
while (true) {
int mid = (high + low) / 2;
V v = list.get(mid);
int compare = v.compareTo(k);
if (compare == 0) {
list.add(mid, k);
break;
} else {
if (compare < 0) {
low = mid;
} else {
high = mid;
}
if (high == low) {
if (list.get(high).compareTo(k) > 0) {
list.add(high, k);
} else {
list.add(high + 1, k);
}
break;
} else if (high - low == 1) {
if (list.get(low).compareTo(k) > 0) {
list.add(low, k);
} else if (list.get(high).compareTo(k) < 0) {
list.add(high + 1, k);
} else {
list.add(high, k);
}
break;
}
}
}
while (list.size() > topN) {
switch (direction) {
case ASC:
list.removeLast();
break;
case DESC:
list.removeFirst();
break;
}
}
}
public List getList() {
List out = new ArrayList();
if (direction == DIRECTION.DESC) {
for (int i = list.size() - 1; i >= 0; i--) {
out.add(list.get(i));
}
} else {
for (int i = 0; i < list.size(); i++) {
out.add(list.get(i));
}
}
return out;
}
public int size() {
return list.size();
}
public static void main(String[] args) {
long stime = System.currentTimeMillis();
TopN list = new TopN(1000, TopN.DIRECTION.DESC);
Random r = new Random();
r.setSeed(System.currentTimeMillis());
for (int i = 0; i < 100000; i++) {
list.add(new Integer(r.nextInt(100000)));
}
System.out.println(list.size() + " : " + list.getList());
long etime = System.currentTimeMillis();
System.out.println((etime - stime) + " ms");
}
}