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add method

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This commit is contained in:
Looly 2021-12-21 23:56:43 +08:00
parent e2710ae79e
commit 9768a4d080
3 changed files with 31 additions and 20 deletions
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1
CHANGELOG.md
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@ -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）

36
hutool-core/src/main/java/cn/hutool/core/collection/CollStreamUtil.java
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@ -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 {
* <B>{@code Collection<E> -------> Map<K,List<E>> } </B>
*
* @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 <E> collection中的泛型
* @param <K> 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 {
* <B>{@code Collection<E> -------> Map<K,List<V>> } </B>
*
* @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 <E> collection中的泛型
* @param <K> map中的key类型
* @param <V> List中的value类型
@ -216,8 +223,8 @@ public class CollStreamUtil {
* <B>{@code Collection<E> -------> Map<K,List<V>> } </B>
*
* @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 <E> collection中的泛型
* @param <K> 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 <K> map中的key类型
* @param <D> 后续操作的返回值
* @return 分组后的map
* @since 5.7.18
*/
public static <E, K, D> Map<K, D> groupThen(Collection<E> collection, Function<E, K> key, Collector<E, ?, D> downstream) {
public static <E, K, D> Map<K, D> groupBy(Collection<E> collection, Function<E, K> key, Collector<E, ?, D> 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 <K> map中的key类型
* @param <D> 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 <E, K, D> Map<K, D> groupThen(Collection<E> collection, Function<E, K> key, Collector<E, ?, D> downstream, boolean isParallel) {
public static <E, K, D> Map<K, D> groupBy(Collection<E> collection, Function<E, K> key, Collector<E, ?, D> downstream, boolean isParallel) {
if (CollUtil.isEmpty(collection)) {
return Collections.emptyMap();
}

14
hutool-core/src/test/java/cn/hutool/core/collection/CollStreamUtilTest.java
View File

@ -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<Long, List<Student>> map = CollStreamUtil.groupThen(null, Student::getTermId, Collectors.toList());
Map<Long, List<Student>> map = CollStreamUtil.groupBy(null, Student::getTermId, Collectors.toList());
Assert.assertEquals(map, Collections.EMPTY_MAP);
// 参数空数组测试
List<Student> 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<Long, Optional<Student>> longOptionalMap = CollStreamUtil.groupThen(list, Student::getTermId, Collectors.maxBy(Comparator.comparing(Student::getClassId)));
Map<Long, Optional<Student>> 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<studentId,name>
Map<Long, HashMap<Long, String>> groupThen = CollStreamUtil.groupThen(list, Student::getTermId, Collector.of(HashMap::new, (m, v) -> m.put(v.getStudentId(), v.getName()), (l, r) -> l));
Map<Long, HashMap<Long, String>> 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())