zhouxy108/hutool
1
0
Fork 0
mirror of https://gitee.com/chinabugotech/hutool.git synced 2025-07-21 15:09:48 +08:00
Code Issues Packages Projects Releases Wiki Activity

新增CollStreamUtil.groupKeyValue(java.util.Collection<E>, java.util.function.Function<E,K>, java.util.function.Function<E,V>)，用于分组时直接获取属性

Browse Source
This commit is contained in:
VampireAchao
2021-12-09 20:13:39 +08:00
committed by achao
parent c1e6ea8d42
commit bc8e9cd159
2 changed files with 60 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

20
hutool-core/src/test/java/cn/hutool/core/collection/CollStreamUtilTest.java
View File

@@ -149,6 +149,26 @@ public class CollStreamUtilTest {
}
@Test
public void testGroupKeyValue() {
Map<Long, List<Long>> map = CollStreamUtil.groupKeyValue(null, Student::getTermId, Student::getClassId);
Assert.assertEquals(map, Collections.EMPTY_MAP);
List<Student> list = new ArrayList<>();
map = CollStreamUtil.groupKeyValue(list, Student::getTermId, Student::getClassId);
Assert.assertEquals(map, Collections.EMPTY_MAP);
list.add(new Student(1, 1, 1, "张三"));
list.add(new Student(1, 2, 1, "李四"));
list.add(new Student(2, 2, 1, "王五"));
map = CollStreamUtil.groupKeyValue(list, Student::getTermId, Student::getClassId);
Map<Long, List<Long>> compare = new HashMap<>();
compare.put(1L, Arrays.asList(1L, 2L));
compare.put(2L, Collections.singletonList(2L));
Assert.assertEquals(compare, map);
}
@Test
public void testTranslate2List() {
List<String> list = CollStreamUtil.toList(null, Student::getName);