!1033 添加解构方法

Merge pull request !1033 from 孔皮皮/v6-dev-List

hutool-core/src/main/java/org/dromara/hutool/core/collection/CollUtil.java

@@ -2354,4 +2354,47 @@ public class CollUtil {
 		}
 		return collection.stream().allMatch(predicate);
 	}
+
+	/**
+	 * 解构多层集合
+	 * 例如：{@code List<List<List<String>>> 解构成 List<String>}
+	 *
+	 * @param collection 需要解构的集合
+	 * @return 解构后的集合
+	 */
+	public static <T> List<T> flat(Collection<?> collection) {
+		return flat(collection, true);
+	}
+
+	/**
+	 * 解构多层集合
+	 * 例如：{@code List<List<List<String>>> 解构成 List<String>}
+	 * <p>
+	 * skipNull如果为true, 则解构后的集合里不包含null值，为false则会包含null值。
+	 *
+	 * @param collection 需要结构的集合
+	 * @param skipNull   是否跳过空的值
+	 * @return 解构后的集合
+	 */
+	@SuppressWarnings({"unchecked"})
+	public static <T> List<T> flat(Collection<?> collection, boolean skipNull) {
+		LinkedList<Object> queue = new LinkedList<>(collection);
+
+		List<Object> result = new ArrayList<>();
+
+		while (!queue.isEmpty()) {
+			Object t = queue.removeFirst();
+
+			if (skipNull && t == null) {
+				continue;
+			}
+
+			if (t instanceof Collection) {
+				queue.addAll((Collection<?>) t);
+			} else {
+				result.add(t);
+			}
+		}
+		return (List<T>) result;
+	}
 }

hutool-core/src/main/java/org/dromara/hutool/core/stream/TransformableWrappedStream.java

@@ -13,6 +13,7 @@
 package org.dromara.hutool.core.stream;
 
 import org.dromara.hutool.core.array.ArrayUtil;
+import org.dromara.hutool.core.collection.CollUtil;
 import org.dromara.hutool.core.collection.ListUtil;
 import org.dromara.hutool.core.collection.iter.IterUtil;
 import org.dromara.hutool.core.lang.Console;
@@ -486,6 +487,17 @@ public interface TransformableWrappedStream<T, S extends TransformableWrappedStr
 		return wrap(flatMap(recursive).peek(e -> childrenSetter.accept(e, null)));
 	}
 
+	/**
+	 * 如果当前元素是集合，则会将集合中的元素解构出来
+	 * 例如：{@code List<List<List<String>>> 解构成 List<String>}
+	 *
+	 * @param <R> 函数执行后返回的List里面的类型
+	 * @return EasyStream 一个流
+	 */
+	default <R> EasyStream<R> flat() {
+		return EasyStream.of(CollUtil.flat(nonNull().collect(Collectors.toList())));
+	}
+
 	// endregion
 
 	// region ============ map ============

hutool-core/src/test/java/org/dromara/hutool/core/collection/CollUtilTest.java

@@ -1,5 +1,6 @@
 package org.dromara.hutool.core.collection;
 
+import lombok.*;
 import org.dromara.hutool.core.collection.iter.IterUtil;
 import org.dromara.hutool.core.collection.set.SetUtil;
 import org.dromara.hutool.core.comparator.CompareUtil;
@@ -7,33 +8,12 @@ import org.dromara.hutool.core.date.DateUtil;
 import org.dromara.hutool.core.lang.Console;
 import org.dromara.hutool.core.map.Dict;
 import org.dromara.hutool.core.map.MapUtil;
+import org.dromara.hutool.core.stream.EasyStream;
 import org.dromara.hutool.core.text.StrUtil;
-import lombok.AllArgsConstructor;
-import lombok.Data;
-import lombok.EqualsAndHashCode;
-import lombok.NoArgsConstructor;
-import lombok.ToString;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
-import java.util.ArrayDeque;
+import java.util.*;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Collection;
-import java.util.Collections;
-import java.util.Comparator;
-import java.util.Date;
-import java.util.HashMap;
-import java.util.HashSet;
-import java.util.LinkedHashSet;
-import java.util.LinkedList;
-import java.util.List;
-import java.util.Map;
-import java.util.Objects;
-import java.util.Queue;
-import java.util.Set;
-import java.util.SortedSet;
-import java.util.Stack;
 import java.util.function.Function;
 
 /**
@@ -1224,4 +1204,52 @@ public class CollUtilTest {
 		final List<Pig> pig = Arrays.asList(new Pig("pig1", 12), new Pig("pig2", 12));
 		Assertions.assertEquals(CollUtil.unionDistinct(dog, cat, pig).size(), 5);
 	}
+
+
+	@Test
+	public void flatListTest1() {
+		List<List<List<String>>> list = Arrays.asList(Arrays.asList(Arrays.asList("1", "2", "3"), Arrays.asList("5", "6", "7")));
+
+		List<Object> objects = CollUtil.flat(list);
+
+		Assertions.assertArrayEquals(new String[]{"1", "2", "3", "5", "6", "7"}, objects.toArray());
+	}
+
+
+	@Test
+	public void flatListTest2() {
+		List<List<List<String>>> list = Arrays.asList(
+			Arrays.asList(
+				Arrays.asList("a"),
+				Arrays.asList("b", "c"),
+				Arrays.asList("d", "e", "f")
+			),
+			Arrays.asList(
+				Arrays.asList("g", "h", "i"),
+				Arrays.asList("j", "k", "l")
+			)
+		);
+		List<Object> flat = CollUtil.flat(list);
+		Assertions.assertArrayEquals(new String[]{"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l"}, flat.toArray());
+
+	}
+
+
+	@Test
+	void flatListTest3() {
+		List<List<List<String>>> list = Arrays.asList(
+			Arrays.asList(
+				Arrays.asList("a"),
+				Arrays.asList("b", "c", null),
+				Arrays.asList("d", "e", "f")
+			),
+			Arrays.asList(
+				Arrays.asList("g", "h", "i"),
+				Arrays.asList("j", "k", "l")
+			)
+		);
+		List<Object> flat = CollUtil.flat(list, false);
+		Assertions.assertArrayEquals(new String[]{"a", "b", "c", null, "d", "e", "f", "g", "h", "i", "j", "k", "l"}, flat.toArray());
+	}
+
 }

hutool-core/src/test/java/org/dromara/hutool/core/stream/AbstractEnhancedWrappedStreamTest.java

@@ -708,4 +708,23 @@ public class AbstractEnhancedWrappedStreamTest {
 		private List<Tree> children;
 	}
 
+
+
+	@Test
+	void test() {
+		List<List<List<String>>> list = Arrays.asList(
+			Arrays.asList(
+				Arrays.asList("a"),
+				Arrays.asList("b", "c"),
+				Arrays.asList("d", "e", "f")
+			),
+			Arrays.asList(
+				Arrays.asList("g", "h", "i"),
+				Arrays.asList("j", "k", "l")
+			)
+		);
+		List<String> r = EasyStream.of(list).<String>flat().toList();
+		Assertions.assertArrayEquals(new String[]{"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l"}, r.toArray());
+	}
+
 }