/
Rankings.java
93 lines (76 loc) · 2.18 KB
/
Rankings.java
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package storm.starter.tools;
import java.io.Serializable;
import java.util.Collections;
import java.util.List;
import com.google.common.collect.Lists;
public class Rankings implements Serializable {
private static final long serialVersionUID = -1549827195410578903L;
private static final int DEFAULT_COUNT = 10;
private final int maxSize;
private final List<Rankable> rankedItems = Lists.newArrayList();
public Rankings() {
this(DEFAULT_COUNT);
}
public Rankings(int topN) {
if (topN < 1) {
throw new IllegalArgumentException("topN must be >= 1");
}
maxSize = topN;
}
/**
* @return the maximum possible number (size) of ranked objects this instance can hold
*/
public int maxSize() {
return maxSize;
}
/**
* @return the number (size) of ranked objects this instance is currently holding
*/
public int size() {
return rankedItems.size();
}
public List<Rankable> getRankings() {
return Lists.newArrayList(rankedItems);
}
public void updateWith(Rankings other) {
for (Rankable r : other.getRankings()) {
updateWith(r);
}
}
public void updateWith(Rankable r) {
addOrReplace(r);
rerank();
shrinkRankingsIfNeeded();
}
private void addOrReplace(Rankable r) {
Integer rank = findRankOf(r);
if (rank != null) {
rankedItems.set(rank, r);
}
else {
rankedItems.add(r);
}
}
private Integer findRankOf(Rankable r) {
Object tag = r.getObject();
for (int rank = 0; rank < rankedItems.size(); rank++) {
Object cur = rankedItems.get(rank).getObject();
if (cur.equals(tag)) {
return rank;
}
}
return null;
}
private void rerank() {
Collections.sort(rankedItems);
Collections.reverse(rankedItems);
}
private void shrinkRankingsIfNeeded() {
if (rankedItems.size() > maxSize) {
rankedItems.remove(maxSize);
}
}
public String toString() {
return rankedItems.toString();
}
}