diff --git a/hutool-core/src/test/java/org/dromara/hutool/core/stream/StreamUtilTest.java b/hutool-core/src/test/java/org/dromara/hutool/core/stream/StreamUtilTest.java
index 670ad924e..034505ed8 100644
--- a/hutool-core/src/test/java/org/dromara/hutool/core/stream/StreamUtilTest.java
+++ b/hutool-core/src/test/java/org/dromara/hutool/core/stream/StreamUtilTest.java
@@ -17,12 +17,7 @@ import org.dromara.hutool.core.collection.set.SetUtil;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Collections;
-import java.util.HashSet;
-import java.util.Iterator;
-import java.util.List;
+import java.util.*;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
@@ -31,7 +26,7 @@ public class StreamUtilTest {
 	@Test
 	void testIterateHierarchies() {
 		// 创建一个三层的树结构，每个节点都有两个子节点
-		Node node = new Node("1", Arrays.asList(
+		final Node node = new Node("1", Arrays.asList(
 			new Node("1-1", Arrays.asList(
 				new Node("1-1-1", null),
 				new Node("1-1-2", null)
@@ -43,20 +38,20 @@ public class StreamUtilTest {
 		));
 
 		// 按广度度优先遍历树结构
-		List<String> allNodes = new ArrayList<>();
+		final List<String> allNodes = new ArrayList<>();
 		StreamUtil.iterateHierarchies(node, node1 -> node1.children)
 			.forEach(node1 -> allNodes.add(node1.id));
 		Assertions.assertEquals(Arrays.asList("1", "1-1", "1-2", "1-1-1", "1-1-2", "1-2-1", "1-2-2"), allNodes);
 
 		// 按广度度优先遍历树结构，忽略id为1-1的节点与以其为根节点的子树
-		List<String> filteredNodes = new ArrayList<>();
+		final List<String> filteredNodes = new ArrayList<>();
 		StreamUtil.iterateHierarchies(node, node1 -> node1.children, node1 -> !node1.id.equals("1-1"))
 			.forEach(node1 -> filteredNodes.add(node1.id));
 		Assertions.assertEquals(Arrays.asList("1", "1-2", "1-2-1", "1-2-2"), filteredNodes);
 	}
 
 	@Test
-	public void ofTest(){
+	public void ofTest() {
 		final Stream<Integer> stream = StreamUtil.of(2, x -> x * 2, 4);
 		final String result = stream.collect(CollectorUtil.joining(","));
 		Assertions.assertEquals("2,4,8,16", result);
@@ -65,7 +60,8 @@ public class StreamUtilTest {
 	// === iterator ===
 	@Test
 	public void streamTestNullIterator() {
-		Assertions.assertThrows(IllegalArgumentException.class, () -> StreamUtil.ofIter(null));
+		final Stream<Object> objectStream = StreamUtil.ofIter(null);
+		Assertions.assertEquals(0, objectStream.count());
 	}
 
 	@SuppressWarnings({"RedundantOperationOnEmptyContainer", "RedundantCollectionOperation"})
@@ -100,11 +96,14 @@ public class StreamUtilTest {
 	private static class Node {
 		private final String id;
 		private List<Node> children;
-		private Node(String id, List<Node> children) {
+
+		private Node(final String id, final List<Node> children) {
 			this.id = id;
 			this.children = children;
 		}
-		public Node(String id) {
+
+		@SuppressWarnings("unused")
+		public Node(final String id) {
 			this.id = id;
 		}
 	}