diff --git a/hutool-core/src/main/java/cn/hutool/core/collection/ListUtil.java b/hutool-core/src/main/java/cn/hutool/core/collection/ListUtil.java
index e21f3aa92..70e69a115 100755
--- a/hutool-core/src/main/java/cn/hutool/core/collection/ListUtil.java
+++ b/hutool-core/src/main/java/cn/hutool/core/collection/ListUtil.java
@@ -685,6 +685,7 @@ public class ListUtil {
 	 * @param otherList 其它列表
 	 * @return 此列表
 	 */
+	@SuppressWarnings("UnusedReturnValue")
 	public static <T> List<T> addAllIfNotContains(final List<T> list, final List<T> otherList) {
 		for (final T t : otherList) {
 			if (false == list.contains(t)) {
@@ -695,12 +696,13 @@ public class ListUtil {
 	}
 
 	/**
+	 * 通过删除或替换现有元素或者原地添加新的元素来修改列表，并以列表形式返回被修改的内容。此方法不会改变原列表。
 	 * 类似js的<a href="https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Global_Objects/Array/splice">splice</a>函数
 	 *
-	 * @param start       起始下标, 可以为负数, -1代表最后一个元素
+	 * @param start       指定修改的开始位置（从 0 计数）, 可以为负数, -1代表最后一个元素
 	 * @param deleteCount 删除个数，必须是正整数
-	 * @param items       放入值
-	 * @return 操作后的流
+	 * @param items       放入的元素
+	 * @return 结果列表
 	 * @since 6.0.0
 	 */
 	@SafeVarargs
diff --git a/hutool-core/src/main/java/cn/hutool/core/lang/Opt.java b/hutool-core/src/main/java/cn/hutool/core/lang/Opt.java
index 66315b586..8b10f1803 100644
--- a/hutool-core/src/main/java/cn/hutool/core/lang/Opt.java
+++ b/hutool-core/src/main/java/cn/hutool/core/lang/Opt.java
@@ -137,7 +137,7 @@ public class Opt<T> {
 	 */
 	@SuppressWarnings("OptionalUsedAsFieldOrParameterType")
 	public static <T> Opt<T> of(Optional<T> optional) {
-		return ofNullable(optional).flattedMap(Function.identity());
+		return ofNullable(optional.orElse(null));
 	}
 
 	/**
diff --git a/hutool-core/src/main/java/cn/hutool/core/lang/Validator.java b/hutool-core/src/main/java/cn/hutool/core/lang/Validator.java
index 850ce1cdb..fa01f02c9 100755
--- a/hutool-core/src/main/java/cn/hutool/core/lang/Validator.java
+++ b/hutool-core/src/main/java/cn/hutool/core/lang/Validator.java
@@ -1063,13 +1063,10 @@ public class Validator {
 		Assert.notNull(value);
 		Assert.notNull(start);
 		Assert.notNull(end);
-		int c1 = DateUtil.compare(value, start);
-		int c2 = DateUtil.compare(value, end);
 
-		if(c1 >= 0 && c2 <= 0){
-			return;
+		if(false == DateUtil.isIn(value, start, end)){
+			throw new ValidateException(errorMsg);
 		}
-		throw new ValidateException(errorMsg);
 	}
 
 	/**
diff --git a/hutool-core/src/main/java/cn/hutool/core/lang/mutable/MutableObj.java b/hutool-core/src/main/java/cn/hutool/core/lang/mutable/MutableObj.java
index c8a9397b2..d78828635 100644
--- a/hutool-core/src/main/java/cn/hutool/core/lang/mutable/MutableObj.java
+++ b/hutool-core/src/main/java/cn/hutool/core/lang/mutable/MutableObj.java
@@ -1,7 +1,6 @@
 package cn.hutool.core.lang.mutable;
 
 import java.io.Serializable;
-import java.util.function.Consumer;
 
 /**
  * 可变{@code Object}
@@ -9,7 +8,7 @@ import java.util.function.Consumer;
  * @param <T> 可变的类型
  * @since 3.0.1
  */
-public class MutableObj<T> implements Mutable<T>, Serializable, Consumer<T> {
+public class MutableObj<T> implements Mutable<T>, Serializable{
 	private static final long serialVersionUID = 1L;
 
 	/**
@@ -51,17 +50,6 @@ public class MutableObj<T> implements Mutable<T>, Serializable, Consumer<T> {
 		this.value = value;
 	}
 
-	/**
-	 * 消费元素
-	 *
-	 * @param t t
-	 * @since 6.0.0
-	 */
-	@Override
-	public void accept(T t) {
-		this.value = t;
-	}
-
 	// -----------------------------------------------------------------------
 	@Override
 	public boolean equals(final Object obj) {
diff --git a/hutool-core/src/main/java/cn/hutool/core/stream/FastStream.java b/hutool-core/src/main/java/cn/hutool/core/stream/FastStream.java
index d07307938..335231acc 100644
--- a/hutool-core/src/main/java/cn/hutool/core/stream/FastStream.java
+++ b/hutool-core/src/main/java/cn/hutool/core/stream/FastStream.java
@@ -938,7 +938,7 @@ public class FastStream<T> implements Stream<T>, Iterable<T> {
 	 */
 	public Optional<T> findLast() {
 		MutableObj<T> last = new MutableObj<>(null);
-		spliterator().forEachRemaining(last);
+		spliterator().forEachRemaining(last::set);
 		return Optional.ofNullable(last.get());
 	}
 
@@ -1226,7 +1226,7 @@ public class FastStream<T> implements Stream<T>, Iterable<T> {
 		// 保存第二个Spliterator的值
 		MutableObj<R> value = new MutableObj<>();
 		// 当两个Spliterator中都还有剩余元素时
-		while (keys.tryAdvance(key) && values.tryAdvance(value)) {
+		while (keys.tryAdvance(key::set) && values.tryAdvance(value::set)) {
 			map.put(key.get(), value.get());
 		}
 		return map;
@@ -1394,7 +1394,7 @@ public class FastStream<T> implements Stream<T>, Iterable<T> {
 		// 保存第二个Spliterator的值
 		MutableObj<U> value = new MutableObj<>();
 		// 当两个Spliterator中都还有剩余元素时
-		while (keys.tryAdvance(key) && values.tryAdvance(value)) {
+		while (keys.tryAdvance(key::set) && values.tryAdvance(value::set)) {
 			list.add(zipper.apply(key.get(), value.get()));
 		}
 		return of(list).parallel(isParallel()).onClose(stream::close);
diff --git a/hutool-core/src/main/java/cn/hutool/core/tree/TreeUtil.java b/hutool-core/src/main/java/cn/hutool/core/tree/TreeUtil.java
index 06853e18e..3537f3815 100644
--- a/hutool-core/src/main/java/cn/hutool/core/tree/TreeUtil.java
+++ b/hutool-core/src/main/java/cn/hutool/core/tree/TreeUtil.java
@@ -6,8 +6,12 @@ import cn.hutool.core.tree.parser.NodeParser;
 import cn.hutool.core.util.ObjUtil;
 
 import java.util.ArrayList;
+import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
+import java.util.Queue;
+import java.util.Stack;
 
 /**
  * 树工具类
@@ -245,7 +249,7 @@ public class TreeUtil {
 	 * @return 森林所有节点列表
 	 */
 	public static <E> List<Tree<E>> deepFirstForestConvertToList(List<Tree<E>> forest) {
-		if (CollectionUtil.isEmpty(forest)) {
+		if (CollUtil.isEmpty(forest)) {
 			return null;
 		}
 		List<Tree<E>> list = new ArrayList<>();
@@ -261,7 +265,7 @@ public class TreeUtil {
 	 * @return 森林所有节点列表
 	 */
 	public static <E> List<Tree<E>> broadFirstForestConvertToList(List<Tree<E>> forest) {
-		if (CollectionUtil.isEmpty(forest)) {
+		if (CollUtil.isEmpty(forest)) {
 			return null;
 		}
 		List<Tree<E>> list = new ArrayList<>();
@@ -297,7 +301,7 @@ public class TreeUtil {
 	}
 
 	/**
-	 * 深度优先,遍历树,将树转换为数组
+	 * 广度优先,遍历树,将树转换为数组
 	 *
 	 * @param root 树的根节点
 	 * @param <E>  节点ID类型
diff --git a/hutool-core/src/test/java/cn/hutool/core/collection/ListUtilTest.java b/hutool-core/src/test/java/cn/hutool/core/collection/ListUtilTest.java
index 2d7bd9dc5..c8d330e88 100644
--- a/hutool-core/src/test/java/cn/hutool/core/collection/ListUtilTest.java
+++ b/hutool-core/src/test/java/cn/hutool/core/collection/ListUtilTest.java
@@ -15,6 +15,7 @@ import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 public class ListUtilTest {
 
@@ -266,4 +267,16 @@ public class ListUtilTest {
 		ListUtil.setOrPadding(list, 3, "a");
 		Assert.assertEquals(4, list.size());
 	}
+
+	@Test
+	public void ofCopyOnWriteTest(){
+		final CopyOnWriteArrayList<String> strings = ListUtil.ofCopyOnWrite(ListUtil.of("a", "b"));
+		Assert.assertEquals(2, strings.size());
+	}
+
+	@Test
+	public void ofCopyOnWriteTest2(){
+		final CopyOnWriteArrayList<String> strings = ListUtil.ofCopyOnWrite("a", "b");
+		Assert.assertEquals(2, strings.size());
+	}
 }