From 9b3414b397248fd59a6039d55cbfb3036de36183 Mon Sep 17 00:00:00 2001
From: Looly <loolly@aliyun.com>
Date: Wed, 12 Nov 2025 22:09:53 +0800
Subject: [PATCH] add test and fix comment

---
 .../java/cn/hutool/core/util/ObjectUtil.java  | 14 ++++----
 .../cn/hutool/core/util/ObjectUtilTest.java   | 35 ++++++++++++++++---
 2 files changed, 38 insertions(+), 11 deletions(-)

diff --git a/hutool-core/src/main/java/cn/hutool/core/util/ObjectUtil.java b/hutool-core/src/main/java/cn/hutool/core/util/ObjectUtil.java
index e49cc85f5..8f08980aa 100644
--- a/hutool-core/src/main/java/cn/hutool/core/util/ObjectUtil.java
+++ b/hutool-core/src/main/java/cn/hutool/core/util/ObjectUtil.java
@@ -72,14 +72,14 @@ public class ObjectUtil {
 	}
 
 	/**
-	 * 计算对象长度，如果是字符串调用其length函数，集合类调用其size函数，数组调用其length属性，其他可遍历对象遍历计算长度<br>
-	 * 支持的类型包括：
+	 * <p>计算对象长度，支持类型包括：
 	 * <ul>
-	 * <li>CharSequence</li>
-	 * <li>Map</li>
-	 * <li>Iterator</li>
-	 * <li>Enumeration</li>
-	 * <li>Array</li>
+	 *     <li>{@code null}：默认返回{@code 0}；</li>
+	 *     <li>数组：返回数组长度；</li>
+	 *     <li>{@link CharSequence}：返回{@link CharSequence#length()}；</li>
+	 *     <li>{@link Collection}：返回{@link Collection#size()}；</li>
+	 *     <li>{@link Iterator}或{@link Iterable}：可迭代的元素数量；副作用：{@link Iterator}只能被迭代一次</li>
+	 *     <li>{@link Enumeration}：返回可迭代的元素数量；副作用：{@link Enumeration}只能被迭代一次</li>
 	 * </ul>
 	 *
 	 * @param obj 被计算长度的对象
diff --git a/hutool-core/src/test/java/cn/hutool/core/util/ObjectUtilTest.java b/hutool-core/src/test/java/cn/hutool/core/util/ObjectUtilTest.java
index 1fd750e38..91a841887 100644
--- a/hutool-core/src/test/java/cn/hutool/core/util/ObjectUtilTest.java
+++ b/hutool-core/src/test/java/cn/hutool/core/util/ObjectUtilTest.java
@@ -4,13 +4,12 @@ import cn.hutool.core.clone.CloneSupport;
 import cn.hutool.core.collection.CollUtil;
 import cn.hutool.core.date.DatePattern;
 import cn.hutool.core.date.DateUtil;
-import static org.junit.jupiter.api.Assertions.*;
 import org.junit.jupiter.api.Test;
 
 import java.time.Instant;
-import java.util.ArrayList;
-import java.util.HashMap;
-import java.util.Map;
+import java.util.*;
+
+import static org.junit.jupiter.api.Assertions.*;
 
 public class ObjectUtilTest {
 
@@ -108,4 +107,32 @@ public class ObjectUtilTest {
 		String a = null;
 		assertFalse(ObjectUtil.isNotNull(a));
 	}
+
+	@Test
+	public void testLengthConsumesIterator() {
+		List<String> list = Arrays.asList("a", "b", "c");
+		Iterator<String> iterator = list.iterator();
+		// 迭代器第一次调用length
+		int length1 = ObjectUtil.length(iterator);
+		assertEquals(3, length1);
+		// 迭代器第二次调用length - 迭代器已经被消耗，返回0
+		int length2 = ObjectUtil.length(iterator);
+		assertEquals(0, length2); // 但当前实现会重新遍历，但iterator已经没有元素了
+		// 尝试使用迭代器 - 已经无法使用
+		assertFalse(iterator.hasNext());
+	}
+
+	@Test
+	public void testLengthConsumesEnumeration() {
+		Vector<String> vector = new Vector<>(Arrays.asList("a", "b", "c"));
+		Enumeration<String> enumeration = vector.elements();
+		// 第一次调用length
+		int length1 = ObjectUtil.length(enumeration);
+		assertEquals(3, length1);
+		// 第二次调用length - 枚举已经被消耗
+		int length2 = ObjectUtil.length(enumeration);
+		assertEquals(0, length2);
+		// 枚举已经无法使用
+		assertFalse(enumeration.hasMoreElements());
+	}
 }