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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} * @return 并集的集合，返回 {@link ArrayList}
*/ */
public static <T> Collection<T> union(Collection<T> coll1, Collection<T> coll2) { public static <T> Collection<T> union(Collection<T> coll1, Collection<T> coll2) {
final ArrayList<T> list = new ArrayList<>();
if (isEmpty(coll1)) { if (isEmpty(coll1)) {
list.addAll(coll2); return new ArrayList<>(coll2);
} else if (isEmpty(coll2)) { } else if (isEmpty(coll2)) {
list.addAll(coll1); return new ArrayList<>(coll1);
} else { }
final Map<T, Integer> map1 = countMap(coll1);
final Map<T, Integer> map2 = countMap(coll2); final ArrayList<T> list = new ArrayList<>(Math.max(coll1.size(), coll2.size()));
final Set<T> elts = newHashSet(coll2); final Map<T, Integer> map1 = countMap(coll1);
elts.addAll(coll1); final Map<T, Integer> map2 = countMap(coll2);
int m; final Set<T> elts = newHashSet(coll2);
for (T t : elts) { elts.addAll(coll1);
m = Math.max(Convert.toInt(map1.get(t), 0), Convert.toInt(map2.get(t), 0)); int m;
for (int i = 0; i < m; i++) { for (T t : elts) {
list.add(t); 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; return list;
@ -226,8 +226,8 @@ public class CollUtil {
* @return 交集的集合，返回 {@link ArrayList} * @return 交集的集合，返回 {@link ArrayList}
*/ */
public static <T> Collection<T> intersection(Collection<T> coll1, Collection<T> coll2) { public static <T> Collection<T> intersection(Collection<T> coll1, Collection<T> coll2) {
final ArrayList<T> list = new ArrayList<>();
if (isNotEmpty(coll1) && isNotEmpty(coll2)) { 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> map1 = countMap(coll1);
final Map<T, Integer> map2 = countMap(coll2); final Map<T, Integer> map2 = countMap(coll2);
final Set<T> elts = newHashSet(coll2); final Set<T> elts = newHashSet(coll2);
@ -238,8 +238,10 @@ public class CollUtil {
list.add(t); list.add(t);
} }
} }
return list;
} }
return list;
return new ArrayList<>();
} }
/** /**