fix 修复反馈不可操纵类型导致后续操纵报错问题

add 新增 filter sorted joining 方法

hutool-core/src/main/java/cn/hutool/core/collection/CollStreamUtil.java

@@ -22,7 +22,7 @@ import java.util.stream.Collectors;
 /**
  * 集合的stream操作封装
  *
- * @author 528910437@QQ.COM, VampireAchao<achao1441470436@gmail.com>
+ * @author 528910437@QQ.COM, VampireAchao<achao1441470436@gmail.com>Lion Li>
  * @since 5.5.2
  */
 public class CollStreamUtil {
@@ -55,7 +55,7 @@ public class CollStreamUtil {
 	 */
 	public static <V, K> Map<K, V> toIdentityMap(Collection<V> collection, Function<V, K> key, boolean isParallel) {
 		if (CollUtil.isEmpty(collection)) {
-			return Collections.emptyMap();
+			return MapUtil.newHashMap();
 		}
 		return toMap(collection, (v) -> Opt.ofNullable(v).map(key).get(), Function.identity(), isParallel);
 	}
@@ -88,7 +88,7 @@ public class CollStreamUtil {
 	 */
 	public static <E, K, V> Map<K, V> toMap(Collection<E> collection, Function<E, K> key, Function<E, V> value, boolean isParallel) {
 		if (CollUtil.isEmpty(collection)) {
-			return Collections.emptyMap();
+			return MapUtil.newHashMap();
 		}
 		return StreamUtil.of(collection, isParallel)
 				.collect(HashMap::new, (m, v) -> m.put(key.apply(v), value.apply(v)), HashMap::putAll);
@@ -122,7 +122,7 @@ public class CollStreamUtil {
 	 */
 	public static <E, K> Map<K, List<E>> groupByKey(Collection<E> collection, Function<E, K> key, boolean isParallel) {
 		if (CollUtil.isEmpty(collection)) {
-			return Collections.emptyMap();
+			return MapUtil.newHashMap();
 		}
 		return groupBy(collection, key, Collectors.toList(), isParallel);
 	}
@@ -160,7 +160,7 @@ public class CollStreamUtil {
 	public static <E, K, U> Map<K, Map<U, List<E>>> groupBy2Key(Collection<E> collection, Function<E, K> key1,
 																Function<E, U> key2, boolean isParallel) {
 		if (CollUtil.isEmpty(collection)) {
-			return Collections.emptyMap();
+			return MapUtil.newHashMap();
 		}
 		return groupBy(collection, key1, CollectorUtil.groupingBy(key2, Collectors.toList()), isParallel);
 	}
@@ -197,7 +197,7 @@ public class CollStreamUtil {
 	public static <E, T, U> Map<T, Map<U, E>> group2Map(Collection<E> collection,
 														Function<E, T> key1, Function<E, U> key2, boolean isParallel) {
 		if (CollUtil.isEmpty(collection) || key1 == null || key2 == null) {
-			return Collections.emptyMap();
+			return MapUtil.newHashMap();
 		}
 		return groupBy(collection, key1, CollectorUtil.toMap(key2, Function.identity(), (l, r) -> l), isParallel);
 	}
@@ -235,7 +235,7 @@ public class CollStreamUtil {
 	public static <E, K, V> Map<K, List<V>> groupKeyValue(Collection<E> collection, Function<E, K> key,
 														  Function<E, V> value, boolean isParallel) {
 		if (CollUtil.isEmpty(collection)) {
-			return Collections.emptyMap();
+			return MapUtil.newHashMap();
 		}
 		return groupBy(collection, key, Collectors.mapping(v -> Opt.ofNullable(v).map(value).orElse(null), Collectors.toList()), isParallel);
 	}
@@ -254,7 +254,7 @@ public class CollStreamUtil {
 	 */
 	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 MapUtil.newHashMap();
 		}
 		return groupBy(collection, key, downstream, false);
 	}
@@ -275,7 +275,7 @@ public class CollStreamUtil {
 	 */
 	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();
+			return MapUtil.newHashMap();
 		}
 		return StreamUtil.of(collection, isParallel).collect(CollectorUtil.groupingBy(key, downstream));
 	}
@@ -307,7 +307,7 @@ public class CollStreamUtil {
 	 */
 	public static <E, T> List<T> toList(Collection<E> collection, Function<E, T> function, boolean isParallel) {
 		if (CollUtil.isEmpty(collection)) {
-			return Collections.emptyList();
+			return CollUtil.newArrayList();
 		}
 		return StreamUtil.of(collection, isParallel)
 				.map(function)
@@ -342,7 +342,7 @@ public class CollStreamUtil {
 	 */
 	public static <E, T> Set<T> toSet(Collection<E> collection, Function<E, T> function, boolean isParallel) {
 		if (CollUtil.isEmpty(collection)) {
-			return Collections.emptySet();
+			return CollUtil.newHashSet();
 		}
 		return StreamUtil.of(collection, isParallel)
 				.map(function)
@@ -365,11 +365,11 @@ public class CollStreamUtil {
 	 */
 	public static <K, X, Y, V> Map<K, V> merge(Map<K, X> map1, Map<K, Y> map2, BiFunction<X, Y, V> merge) {
 		if (MapUtil.isEmpty(map1) && MapUtil.isEmpty(map2)) {
-			return Collections.emptyMap();
+			return MapUtil.newHashMap();
 		} else if (MapUtil.isEmpty(map1)) {
-			map1 = Collections.emptyMap();
+			map1 = MapUtil.newHashMap();
 		} else if (MapUtil.isEmpty(map2)) {
-			map2 = Collections.emptyMap();
+			map2 = MapUtil.newHashMap();
 		}
 		Set<K> key = new HashSet<>();
 		key.addAll(map1.keySet());
@@ -385,4 +385,58 @@ public class CollStreamUtil {
 		}
 		return map;
 	}
+
+	/**
+     * 将collection过滤
+     *
+     * @param collection 需要转化的集合
+     * @param function   过滤方法
+     * @return 过滤后的list
+     */
+    public static <E> List<E> filter(Collection<E> collection, Predicate<E> function) {
+        if (CollUtil.isEmpty(collection)) {
+            return CollUtil.newArrayList();
+        }
+        return collection.stream().filter(function).collect(Collectors.toList());
+    }
+
+    /**
+     * 将collection拼接
+     *
+     * @param collection 需要转化的集合
+     * @param function   拼接方法
+     * @return 拼接后的list
+     */
+    public static <E> String join(Collection<E> collection, Function<E, String> function) {
+        return join(collection, function, ",");
+    }
+
+    /**
+     * 将collection拼接
+     *
+     * @param collection 需要转化的集合
+     * @param function   拼接方法
+     * @param delimiter  拼接符
+     * @return 拼接后的list
+     */
+    public static <E> String join(Collection<E> collection, Function<E, String> function, CharSequence delimiter) {
+        if (CollUtil.isEmpty(collection)) {
+            return StrUtil.EMPTY;
+        }
+        return collection.stream().map(function).filter(Objects::nonNull).collect(Collectors.joining(delimiter));
+    }
+
+    /**
+     * 将collection排序
+     *
+     * @param collection 需要转化的集合
+     * @param comparing  排序方法
+     * @return 排序后的list
+     */
+    public static <E> List<E> sorted(Collection<E> collection, Comparator<E> comparing) {
+        if (CollUtil.isEmpty(collection)) {
+            return CollUtil.newArrayList();
+        }
+        return collection.stream().sorted(comparing).collect(Collectors.toList());
+    }
 }