diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2ac6a595a..0187dde38 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,7 @@
* 【log 】 log4j2的编译依赖改为api，core为test依赖（pr#2019@Github）
* 【core 】 Img.scale缩小默认使用平滑模式，增加scale方法重载可选模式（issue#I4MY6X@Gitee）
* 【core 】 excel添加写入图片的方法（pr#486@Gitee）
+* 【core 】 增加CollStreamUtil.groupBy（pr#484@Gitee）
*
### 🐞Bug修复
* 【core 】 LineReadWatcher#onModify文件清空判断问题（issue#2013@Github）
diff --git a/hutool-core/src/main/java/cn/hutool/core/collection/CollStreamUtil.java b/hutool-core/src/main/java/cn/hutool/core/collection/CollStreamUtil.java
index ce2eb5d27..51a9c3eee 100644
--- a/hutool-core/src/main/java/cn/hutool/core/collection/CollStreamUtil.java
+++ b/hutool-core/src/main/java/cn/hutool/core/collection/CollStreamUtil.java
@@ -5,7 +5,14 @@ import cn.hutool.core.lang.Opt;
import cn.hutool.core.map.MapUtil;
import cn.hutool.core.stream.StreamUtil;
-import java.util.*;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
import java.util.function.BiFunction;
import java.util.function.Function;
import java.util.stream.Collector;
@@ -106,7 +113,7 @@ public class CollStreamUtil {
* {@code Collection -------> Map> }
*
* @param collection 需要分组的集合
- * @param key 分组的规则
+ * @param key 键分组的规则
* @param isParallel 是否并行流
* @param collection中的泛型
* @param map中的key类型
@@ -116,7 +123,7 @@ public class CollStreamUtil {
if (CollUtil.isEmpty(collection)) {
return Collections.emptyMap();
}
- return groupThen(collection, key, Collectors.toList(), isParallel);
+ return groupBy(collection, key, Collectors.toList(), isParallel);
}
/**
@@ -154,7 +161,7 @@ public class CollStreamUtil {
if (CollUtil.isEmpty(collection)) {
return Collections.emptyMap();
}
- return groupThen(collection, key1, Collectors.groupingBy(key2, Collectors.toList()), isParallel);
+ return groupBy(collection, key1, Collectors.groupingBy(key2, Collectors.toList()), isParallel);
}
/**
@@ -191,7 +198,7 @@ public class CollStreamUtil {
if (CollUtil.isEmpty(collection) || key1 == null || key2 == null) {
return Collections.emptyMap();
}
- return groupThen(collection, key1, Collectors.toMap(key2, Function.identity(), (l, r) -> l), isParallel);
+ return groupBy(collection, key1, Collectors.toMap(key2, Function.identity(), (l, r) -> l), isParallel);
}
/**
@@ -199,8 +206,8 @@ public class CollStreamUtil {
* {@code Collection -------> Map> }
*
* @param collection 需要分组的集合
- * @param key 分组的规则
- * @param value 分组的规则
+ * @param key 键分组的规则
+ * @param value 值分组的规则
* @param collection中的泛型
* @param map中的key类型
* @param List中的value类型
@@ -216,8 +223,8 @@ public class CollStreamUtil {
* {@code Collection -------> Map> }
*
* @param collection 需要分组的集合
- * @param key 分组的规则
- * @param value 分组的规则
+ * @param key 键分组的规则
+ * @param value 值分组的规则
* @param isParallel 是否并行流
* @param collection中的泛型
* @param map中的key类型
@@ -229,7 +236,7 @@ public class CollStreamUtil {
if (CollUtil.isEmpty(collection)) {
return Collections.emptyMap();
}
- return groupThen(collection, key, Collectors.mapping(value, Collectors.toList()), isParallel);
+ return groupBy(collection, key, Collectors.mapping(value, Collectors.toList()), isParallel);
}
/**
@@ -242,12 +249,13 @@ public class CollStreamUtil {
* @param map中的key类型
* @param 后续操作的返回值
* @return 分组后的map
+ * @since 5.7.18
*/
- public static Map groupThen(Collection collection, Function key, Collector downstream) {
+ public static Map groupBy(Collection collection, Function key, Collector downstream) {
if (CollUtil.isEmpty(collection)) {
return Collections.emptyMap();
}
- return groupThen(collection, key, downstream, false);
+ return groupBy(collection, key, downstream, false);
}
/**
@@ -261,8 +269,10 @@ public class CollStreamUtil {
* @param map中的key类型
* @param 后续操作的返回值
* @return 分组后的map
+ * @see Collectors#groupingBy(Function, Collector)
+ * @since 5.7.18
*/
- public static Map groupThen(Collection collection, Function key, Collector downstream, boolean isParallel) {
+ public static Map groupBy(Collection collection, Function key, Collector downstream, boolean isParallel) {
if (CollUtil.isEmpty(collection)) {
return Collections.emptyMap();
}
diff --git a/hutool-core/src/test/java/cn/hutool/core/collection/CollStreamUtilTest.java b/hutool-core/src/test/java/cn/hutool/core/collection/CollStreamUtilTest.java
index feaa8b393..63d5faa56 100644
--- a/hutool-core/src/test/java/cn/hutool/core/collection/CollStreamUtilTest.java
+++ b/hutool-core/src/test/java/cn/hutool/core/collection/CollStreamUtilTest.java
@@ -8,7 +8,6 @@ import org.junit.Assert;
import org.junit.Test;
import java.util.*;
-import java.util.function.Function;
import java.util.stream.Collector;
import java.util.stream.Collectors;
@@ -173,16 +172,16 @@ public class CollStreamUtilTest {
}
@Test
- public void testGroupThen() {
- // groupThen作为之前所有group函数的公共部分抽取出来，并更接近于jdk原生，灵活性更强
+ public void testGroupBy() {
+ // groupBy作为之前所有group函数的公共部分抽取出来，并更接近于jdk原生，灵活性更强
// 参数null测试
- Map> map = CollStreamUtil.groupThen(null, Student::getTermId, Collectors.toList());
+ Map> map = CollStreamUtil.groupBy(null, Student::getTermId, Collectors.toList());
Assert.assertEquals(map, Collections.EMPTY_MAP);
// 参数空数组测试
List list = new ArrayList<>();
- map = CollStreamUtil.groupThen(list, Student::getTermId, Collectors.toList());
+ map = CollStreamUtil.groupBy(list, Student::getTermId, Collectors.toList());
Assert.assertEquals(map, Collections.EMPTY_MAP);
// 放入元素
@@ -190,11 +189,12 @@ public class CollStreamUtilTest {
list.add(new Student(1, 2, 1, "李四"));
list.add(new Student(2, 2, 1, "王五"));
// 先根据termId分组，再通过classId比较，找出最大值所属的那个Student,返回的Optional
- Map> longOptionalMap = CollStreamUtil.groupThen(list, Student::getTermId, Collectors.maxBy(Comparator.comparing(Student::getClassId)));
+ Map> longOptionalMap = CollStreamUtil.groupBy(list, Student::getTermId, Collectors.maxBy(Comparator.comparing(Student::getClassId)));
+ //noinspection OptionalGetWithoutIsPresent
Assert.assertEquals("李四", longOptionalMap.get(1L).get().getName());
// 先根据termId分组，再转换为Map
- Map> groupThen = CollStreamUtil.groupThen(list, Student::getTermId, Collector.of(HashMap::new, (m, v) -> m.put(v.getStudentId(), v.getName()), (l, r) -> l));
+ Map> groupThen = CollStreamUtil.groupBy(list, Student::getTermId, Collector.of(HashMap::new, (m, v) -> m.put(v.getStudentId(), v.getName()), (l, r) -> l));
Assert.assertEquals(
MapUtil.builder()
.put(1L, MapUtil.builder().put(1L, "李四").build())