diff --git a/hutool-core/src/main/java/cn/hutool/core/date/StopWatch.java b/hutool-core/src/main/java/cn/hutool/core/date/StopWatch.java
index 7a3056a3c..121d52dda 100755
--- a/hutool-core/src/main/java/cn/hutool/core/date/StopWatch.java
+++ b/hutool-core/src/main/java/cn/hutool/core/date/StopWatch.java
@@ -19,8 +19,8 @@ import java.util.concurrent.TimeUnit;
  * <p>
  * 使用方法如下：
  *
- * <pre>
- * StopWatch stopWatch = new StopWatch("任务名称");
+ * <pre>{@code
+ * StopWatch stopWatch = StopWatch.of("任务名称");
  *
  * // 任务1
  * stopWatch.start("任务一");
@@ -35,13 +35,22 @@ import java.util.concurrent.TimeUnit;
  * // 打印出耗时
  * Console.log(stopWatch.prettyPrint());
  *
- * </pre>
+ * }</pre>
  *
  * @author Spring Framework, Looly
  * @since 4.6.6
  */
 public class StopWatch {
 
+	/**
+	 * 创建计时任务（秒表）
+	 *
+	 * @return StopWatch
+	 */
+	public static StopWatch of() {
+		return new StopWatch();
+	}
+
 	/**
 	 * 创建计时任务（秒表）
 	 *
diff --git a/hutool-core/src/main/java/cn/hutool/core/io/FastStringWriter.java b/hutool-core/src/main/java/cn/hutool/core/io/FastStringWriter.java
index f45e39bfb..9744e9fa8 100644
--- a/hutool-core/src/main/java/cn/hutool/core/io/FastStringWriter.java
+++ b/hutool-core/src/main/java/cn/hutool/core/io/FastStringWriter.java
@@ -8,6 +8,7 @@ import java.io.Writer;
  * @author looly
  * @since 5.3.3
  */
+@SuppressWarnings("NullableProblems")
 public final class FastStringWriter extends Writer {
 
 	private static final int DEFAULT_CAPACITY = 16;
diff --git a/hutool-core/src/main/java/cn/hutool/core/io/ManifestUtil.java b/hutool-core/src/main/java/cn/hutool/core/util/ManifestUtil.java
similarity index 97%
rename from hutool-core/src/main/java/cn/hutool/core/io/ManifestUtil.java
rename to hutool-core/src/main/java/cn/hutool/core/util/ManifestUtil.java
index 030e10b0e..8e0cafa5b 100644
--- a/hutool-core/src/main/java/cn/hutool/core/io/ManifestUtil.java
+++ b/hutool-core/src/main/java/cn/hutool/core/util/ManifestUtil.java
@@ -1,5 +1,6 @@
-package cn.hutool.core.io;
+package cn.hutool.core.util;
 
+import cn.hutool.core.io.IORuntimeException;
 import cn.hutool.core.io.resource.ResourceUtil;
 
 import java.io.File;
diff --git a/hutool-core/src/test/java/cn/hutool/core/io/FastStringWriterTest.java b/hutool-core/src/test/java/cn/hutool/core/io/FastStringWriterTest.java
new file mode 100755
index 000000000..c9fa99a44
--- /dev/null
+++ b/hutool-core/src/test/java/cn/hutool/core/io/FastStringWriterTest.java
@@ -0,0 +1,17 @@
+package cn.hutool.core.io;
+
+import cn.hutool.core.text.StrUtil;
+import org.junit.Assert;
+import org.junit.Test;
+
+public class FastStringWriterTest {
+
+	@SuppressWarnings("resource")
+	@Test
+	public void writeTest() {
+		final FastStringWriter fastStringWriter = new FastStringWriter(IoUtil.DEFAULT_BUFFER_SIZE);
+		fastStringWriter.write(StrUtil.repeat("hutool", 2));
+
+		Assert.assertEquals("hutoolhutool", fastStringWriter.toString());
+	}
+}
diff --git a/hutool-core/src/test/java/cn/hutool/core/io/ManifestUtilTest.java b/hutool-core/src/test/java/cn/hutool/core/io/ManifestUtilTest.java
index 86f90ad85..cfa6b33f6 100644
--- a/hutool-core/src/test/java/cn/hutool/core/io/ManifestUtilTest.java
+++ b/hutool-core/src/test/java/cn/hutool/core/io/ManifestUtilTest.java
@@ -1,5 +1,6 @@
 package cn.hutool.core.io;
 
+import cn.hutool.core.util.ManifestUtil;
 import org.junit.Assert;
 import org.junit.Test;