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Merge pull request #1110 from nickChenyx/v5-dev

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交并集结果集合设置初始化大小，避免扩容成本
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Golden Looly 2020-09-23 14:38:05 +08:00 committed by GitHub
commit c7a8aed325
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1 changed files with 18 additions and 16 deletions
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34
hutool-core/src/main/java/cn/hutool/core/collection/CollUtil.java
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@ -104,22 +104,22 @@ public class CollUtil {
* @return 并集的集合，返回 {@link ArrayList}
*/
public static <T> Collection<T> union(Collection<T> coll1, Collection<T> coll2) {
final ArrayList<T> list = new ArrayList<>();
if (isEmpty(coll1)) {
list.addAll(coll2);
return new ArrayList<>(coll2);
} else if (isEmpty(coll2)) {
list.addAll(coll1);
} else {
final Map<T, Integer> map1 = countMap(coll1);
final Map<T, Integer> map2 = countMap(coll2);
final Set<T> elts = newHashSet(coll2);
elts.addAll(coll1);
int m;
for (T t : elts) {
m = Math.max(Convert.toInt(map1.get(t), 0), Convert.toInt(map2.get(t), 0));
for (int i = 0; i < m; i++) {
list.add(t);
}
return new ArrayList<>(coll1);
}
final ArrayList<T> list = new ArrayList<>(Math.max(coll1.size(), coll2.size()));
final Map<T, Integer> map1 = countMap(coll1);
final Map<T, Integer> map2 = countMap(coll2);
final Set<T> elts = newHashSet(coll2);
elts.addAll(coll1);
int m;
for (T t : elts) {
m = Math.max(Convert.toInt(map1.get(t), 0), Convert.toInt(map2.get(t), 0));
for (int i = 0; i < m; i++) {
list.add(t);
}
}
return list;
@ -226,8 +226,8 @@ public class CollUtil {
* @return 交集的集合，返回 {@link ArrayList}
*/
public static <T> Collection<T> intersection(Collection<T> coll1, Collection<T> coll2) {
final ArrayList<T> list = new ArrayList<>();
if (isNotEmpty(coll1) && isNotEmpty(coll2)) {
final ArrayList<T> list = new ArrayList<>(Math.min(coll1.size(), coll2.size()));
final Map<T, Integer> map1 = countMap(coll1);
final Map<T, Integer> map2 = countMap(coll2);
final Set<T> elts = newHashSet(coll2);
@ -238,8 +238,10 @@ public class CollUtil {
list.add(t);
}
}
return list;
}
return list;
return new ArrayList<>();
}
/**