--- a/src/jdk.javadoc/share/classes/jdk/javadoc/internal/tool/JavadocTool.java	Thu Feb 21 15:05:47 2019 -0800
+++ b/src/jdk.javadoc/share/classes/jdk/javadoc/internal/tool/JavadocTool.java	Thu Feb 21 15:17:42 2019 -0800
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2019, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -25,8 +25,9 @@
 
 package jdk.javadoc.internal.tool;
 
-
-import java.io.File;
+import java.nio.file.Files;
+import java.nio.file.InvalidPathException;
+import java.nio.file.Paths;
 import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.LinkedHashSet;
@@ -165,7 +166,7 @@
             // Normally, the args should be a series of package names or file names.
             // Parse the files and collect the package names.
             for (String arg: javaNames) {
-                if (fm != null && arg.endsWith(".java") && new File(arg).exists()) {
+                if (fm != null && arg.endsWith(".java") && isRegularFile(arg)) {
                     parse(fm.getJavaFileObjects(arg), classTrees, true);
                 } else if (isValidPackageName(arg)) {
                     packageNames.add(arg);
@@ -247,6 +248,14 @@
         return toolEnv.docEnv;
     }
 
+    private boolean isRegularFile(String s) {
+        try {
+            return Files.isRegularFile(Paths.get(s));
+        } catch (InvalidPathException e) {
+            return false;
+        }
+    }
+
     /** Is the given string a valid package name? */
     boolean isValidPackageName(String s) {
         if (s.contains("/")) {

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/langtools/jdk/javadoc/doclet/testJavaPackage/TestJavaPackage.java	Thu Feb 21 15:17:42 2019 -0800
@@ -0,0 +1,86 @@
+/*
+ * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug     8216170
+ * @summary java.lang.IllegalArgumentException: directories not supported
+ * @library /tools/lib ../../lib
+ * @modules jdk.compiler/com.sun.tools.javac.api
+ *          jdk.compiler/com.sun.tools.javac.main
+ *          jdk.javadoc/jdk.javadoc.internal.api
+ *          jdk.javadoc/jdk.javadoc.internal.tool
+ * @build toolbox.ToolBox javadoc.tester.*
+ * @run main TestJavaPackage
+ */
+
+import java.io.IOException;
+import java.nio.file.Path;
+
+import toolbox.ModuleBuilder;
+import toolbox.ToolBox;
+
+import javadoc.tester.JavadocTester;
+
+public class TestJavaPackage extends JavadocTester {
+    public static void main(String... args) throws Exception {
+        TestJavaPackage tester = new TestJavaPackage();
+        tester.runTests();
+    }
+
+    private final ToolBox tb = new ToolBox();
+
+    @Test
+    public void testPackage() throws IOException {
+        Path src = Path.of("src");
+        tb.writeJavaFiles(src,
+            "module com.example.java { exports com.example.java; }",
+            "package com.example.java; public class C { }");
+
+        // Disable the standard check that the output directory is empty.
+        // It is a significant part of the test case that the output directory
+        // is set to the current directory, which (in this case) also contains
+        // the src/ directory.
+        setOutputDirectoryCheck(DirectoryCheck.NONE);
+
+        javadoc("-d", ".",  // using "." is important for the test case
+                "-sourcepath", src.toString(),
+                "com.example.java");
+        checkExit(Exit.OK);
+        checkFiles(true,
+            "com.example.java/com/example/java/C.html");
+
+        // repeat the call, to verify the package name "com.example.java" is not
+        // confused with the output directory for the "com.example.java" module,
+        // created by the first call
+
+        javadoc("-d", ".",  // using "." is important for the test case
+                "-sourcepath", src.toString(),
+                "com.example.java");
+        checkExit(Exit.OK);
+        checkFiles(true,
+            "com.example.java/com/example/java/C.html");
+    }
+}
+
+