--- a/langtools/src/java.compiler/share/classes/javax/tools/StandardJavaFileManager.java	Wed May 11 20:28:22 2016 +0000
+++ b/langtools/src/java.compiler/share/classes/javax/tools/StandardJavaFileManager.java	Thu May 12 11:36:08 2016 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2006, 2015, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2006, 2016, 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
@@ -29,6 +29,7 @@
 import java.io.IOException;
 import java.nio.file.Path;
 import java.util.Arrays;
+import java.util.Collection;
 
 import static javax.tools.FileManagerUtils.*;
 
@@ -176,7 +177,8 @@
     /**
      * Returns file objects representing the given paths.
      *
-     * <p>The default implementation converts each path to a file and calls
+     * @implSpec
+     * The default implementation converts each path to a file and calls
      * {@link #getJavaFileObjectsFromFiles getJavaObjectsFromFiles}.
      * IllegalArgumentException will be thrown if any of the paths
      * cannot be converted to a file.
@@ -280,10 +282,21 @@
      * Associates the given search path with the given location.  Any
      * previous value will be discarded.
      *
-     * <p>The default implementation converts each path to a file and calls
+     * @apiNote
+     * The type of the {@code paths} parameter is a {@code Collection}
+     * and not {@code Iterable}. This is to prevent the possibility of
+     * accidentally calling the method with a single {@code Path} as
+     * the second argument, because although {@code Path} implements
+     * {@code Iterable<Path>}, it would almost never be correct to call
+     * this method with a single {@code Path} and have it be treated as
+     * an {@code Iterable} of its components.
+     *
+     *
+     * @implSpec
+     * The default implementation converts each path to a file and calls
      * {@link #getJavaFileObjectsFromFiles getJavaObjectsFromFiles}.
      * IllegalArgumentException will be thrown if any of the paths
-     * cannot be converted to a file.</p>
+     * cannot be converted to a file.
      *
      * @param location a location
      * @param paths a list of paths, if {@code null} use the default
@@ -297,8 +310,8 @@
      *
      * @since 9
      */
-    default void setLocationFromPaths(Location location, Iterable<? extends Path> paths)
-        throws IOException {
+    default void setLocationFromPaths(Location location, Collection<? extends Path> paths)
+            throws IOException {
         setLocation(location, asFiles(paths));
     }
 
@@ -319,6 +332,11 @@
     /**
      * Returns the search path associated with the given location.
      *
+     * @implSpec
+     * The default implementation calls {@link #getLocation getLocation}
+     * and then returns an {@code Iterable} formed by calling {@code toPath()}
+     * on each {@code File} returned from {@code getLocation}.
+     *
      * @param location a location
      * @return a list of paths or {@code null} if this location has no
      * associated search path
@@ -337,8 +355,9 @@
      * {@link java.nio.file.Path Path} object. In such cases, this method may be
      * used to access that object.
      *
-     * <p>The default implementation throws {@link UnsupportedOperationException}
-     * for all files.</p>
+     * @implSpec
+     * The default implementation throws {@link UnsupportedOperationException}
+     * for all files.
      *
      * @param file a file object
      * @return a path representing the same underlying file system artifact
@@ -351,4 +370,36 @@
         throw new UnsupportedOperationException();
     }
 
+    /**
+     * Factory to create {@code Path} objects from strings.
+     *
+     * @since 9
+     */
+    interface PathFactory {
+        /**
+         * Converts a path string, or a sequence of strings that when joined form a path string, to a Path.
+         *
+         * @param first  the path string or initial part of the path string
+         * @param more   additional strings to be joined to form the path string
+         * @return       the resulting {@code Path}
+         */
+        Path getPath(String first, String... more);
+    }
+
+     /**
+      * Specify a factory that can be used to generate a path from a string, or series of strings.
+      *
+      * If this method is not called, a factory whose {@code getPath} method is
+      * equivalent to calling
+      * {@link java.nio.file.Paths#get(String, String...) java.nio.file.Paths.get(first, more)}
+      * will be used.
+      *
+      * @implSpec
+      * The default implementation of this method ignores the factory that is provided.
+      *
+      * @param f  the factory
+      *
+      * @since 9
+      */
+    default void setPathFactory(PathFactory f) { }
 }

--- a/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/api/ClientCodeWrapper.java	Wed May 11 20:28:22 2016 +0000
+++ b/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/api/ClientCodeWrapper.java	Thu May 12 11:36:08 2016 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011, 2015, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2011, 2016, 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
@@ -492,7 +492,7 @@
         }
 
         @Override @DefinedBy(Api.COMPILER)
-        public void setLocationFromPaths(Location location, Iterable<? extends Path> paths) throws IOException {
+        public void setLocationFromPaths(Location location, Collection<? extends Path> paths) throws IOException {
             try {
                 ((StandardJavaFileManager)clientJavaFileManager).setLocationFromPaths(location, paths);
             } catch (ClientCodeException e) {
@@ -534,6 +534,17 @@
                 throw new ClientCodeException(e);
             }
         }
+
+        @Override @DefinedBy(Api.COMPILER)
+        public void setPathFactory(PathFactory f) {
+            try {
+                ((StandardJavaFileManager)clientJavaFileManager).setPathFactory(f);
+            } catch (ClientCodeException e) {
+                throw e;
+            } catch (RuntimeException | Error e) {
+                throw new ClientCodeException(e);
+            }
+        }
     }
 
     protected class WrappedFileObject implements FileObject {

--- a/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/file/FSInfo.java	Wed May 11 20:28:22 2016 +0000
+++ b/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/file/FSInfo.java	Thu May 12 11:36:08 2016 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2015, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2016, 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
@@ -26,6 +26,7 @@
 package com.sun.tools.javac.file;
 
 import java.io.IOException;
+import java.nio.file.FileSystems;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
@@ -108,7 +109,7 @@
             for (StringTokenizer st = new StringTokenizer(path);
                  st.hasMoreTokens(); ) {
                 String elt = st.nextToken();
-                Path f = Paths.get(elt);
+                Path f = FileSystems.getDefault().getPath(elt);
                 if (!f.isAbsolute() && parent != null)
                     f = parent.resolve(f).toAbsolutePath();
                 list.add(f);

--- a/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/file/JavacFileManager.java	Wed May 11 20:28:22 2016 +0000
+++ b/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/file/JavacFileManager.java	Thu May 12 11:36:08 2016 -0700
@@ -109,6 +109,8 @@
 
     protected boolean symbolFileEnabled;
 
+    private PathFactory pathFactory = Paths::get;
+
     protected enum SortFiles implements Comparator<Path> {
         FORWARD {
             @Override
@@ -166,6 +168,16 @@
         }
     }
 
+    @Override @DefinedBy(DefinedBy.Api.COMPILER)
+    public void setPathFactory(PathFactory f) {
+        pathFactory = Objects.requireNonNull(f);
+        locations.setPathFactory(f);
+    }
+
+    private Path getPath(String first, String... more) {
+        return pathFactory.getPath(first, more);
+    }
+
     /**
      * Set whether or not to use ct.sym as an alternate to rt.jar.
      */
@@ -199,7 +211,7 @@
     public Iterable<? extends JavaFileObject> getJavaFileObjectsFromStrings(Iterable<String> names) {
         ListBuffer<Path> paths = new ListBuffer<>();
         for (String name : names)
-            paths.append(Paths.get(nullCheck(name)));
+            paths.append(getPath(nullCheck(name)));
         return getJavaFileObjectsFromPaths(paths.toList());
     }
 
@@ -837,7 +849,7 @@
                 if (sibling != null && sibling instanceof PathFileObject) {
                     return ((PathFileObject) sibling).getSibling(baseName);
                 } else {
-                    Path p = Paths.get(baseName);
+                    Path p = getPath(baseName);
                     Path real = fsInfo.getCanonicalFile(p);
                     return PathFileObject.forSimplePath(this, real, p);
                 }
@@ -855,7 +867,7 @@
 
         try {
             if (dir == null) {
-                dir = Paths.get(System.getProperty("user.dir"));
+                dir = getPath(System.getProperty("user.dir"));
             }
             Path path = fileName.resolveAgainst(fsInfo.getCanonicalFile(dir));
             return PathFileObject.forDirectoryPath(this, path, dir, fileName);
@@ -918,7 +930,7 @@
 
     @Override @DefinedBy(Api.COMPILER)
     public void setLocationFromPaths(Location location,
-                            Iterable<? extends Path> searchpath)
+                            Collection<? extends Path> searchpath)
         throws IOException
     {
         nullCheck(location);

--- a/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/file/Locations.java	Wed May 11 20:28:22 2016 +0000
+++ b/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/file/Locations.java	Thu May 12 11:36:08 2016 -0700
@@ -68,6 +68,7 @@
 import javax.tools.JavaFileManager;
 import javax.tools.JavaFileManager.Location;
 import javax.tools.StandardJavaFileManager;
+import javax.tools.StandardJavaFileManager.PathFactory;
 import javax.tools.StandardLocation;
 
 import com.sun.tools.javac.code.Lint;
@@ -121,7 +122,9 @@
 
     private ModuleNameReader moduleNameReader;
 
-    static final Path javaHome = Paths.get(System.getProperty("java.home"));
+    private PathFactory pathFactory = Paths::get;
+
+    static final Path javaHome = FileSystems.getDefault().getPath(System.getProperty("java.home"));
     static final Path thisSystemModules = javaHome.resolve("lib").resolve("modules");
 
     Map<Path, FileSystem> fileSystems = new LinkedHashMap<>();
@@ -131,6 +134,10 @@
         initHandlers();
     }
 
+    Path getPath(String first, String... more) {
+        return pathFactory.getPath(first, more);
+    }
+
     public void close() throws IOException {
         ListBuffer<IOException> list = new ListBuffer<>();
         closeables.forEach(closeable -> {
@@ -155,6 +162,10 @@
         this.fsInfo = fsInfo;
     }
 
+    void setPathFactory(PathFactory f) {
+        pathFactory = f;
+    }
+
     boolean isDefaultBootClassPath() {
         BootClassPathLocationHandler h
                 = (BootClassPathLocationHandler) getHandler(PLATFORM_CLASS_PATH);
@@ -167,7 +178,7 @@
      * @param searchPath The search path to be split
      * @return The elements of the path
      */
-    private static Iterable<Path> getPathEntries(String searchPath) {
+    private Iterable<Path> getPathEntries(String searchPath) {
         return getPathEntries(searchPath, null);
     }
 
@@ -181,7 +192,7 @@
      * empty path elements
      * @return The elements of the path
      */
-    private static Iterable<Path> getPathEntries(String searchPath, Path emptyPathDefault) {
+    private Iterable<Path> getPathEntries(String searchPath, Path emptyPathDefault) {
         ListBuffer<Path> entries = new ListBuffer<>();
         for (String s: searchPath.split(Pattern.quote(File.pathSeparator), -1)) {
             if (s.isEmpty()) {
@@ -189,7 +200,7 @@
                     entries.add(emptyPathDefault);
                 }
             } else {
-                entries.add(Paths.get(s));
+                entries.add(getPath(s));
             }
         }
         return entries;
@@ -465,7 +476,7 @@
             // need to decide how best to report issue for benefit of
             // direct API call on JavaFileManager.handleOption(specifies IAE)
             // vs. command line decoding.
-            outputDir = (value == null) ? null : Paths.get(value);
+            outputDir = (value == null) ? null : getPath(value);
             return true;
         }
 
@@ -606,7 +617,7 @@
         protected SearchPath createPath() {
             return new SearchPath()
                     .expandJarClassPaths(true) // Only search user jars for Class-Paths
-                    .emptyPathDefault(Paths.get("."));  // Empty path elt ==> current directory
+                    .emptyPathDefault(getPath("."));  // Empty path elt ==> current directory
         }
 
         private void lazy() {
@@ -791,7 +802,7 @@
             paths.addAll(modules);
 
             for (String s : files.split(Pattern.quote(File.pathSeparator))) {
-                paths.add(Paths.get(s));
+                paths.add(getPath(s));
             }
 
             return paths;
@@ -1170,12 +1181,12 @@
             for (String seg: segments) {
                 int markStart = seg.indexOf(MARKER);
                 if (markStart == -1) {
-                    add(map, Paths.get(seg), null);
+                    add(map, getPath(seg), null);
                 } else {
                     if (markStart == 0 || !isSeparator(seg.charAt(markStart - 1))) {
                         throw new IllegalArgumentException("illegal use of " + MARKER + " in " + seg);
                     }
-                    Path prefix = Paths.get(seg.substring(0, markStart - 1));
+                    Path prefix = getPath(seg.substring(0, markStart - 1));
                     Path suffix;
                     int markEnd = markStart + MARKER.length();
                     if (markEnd == seg.length()) {
@@ -1184,7 +1195,7 @@
                             || seg.indexOf(MARKER, markEnd) != -1) {
                         throw new IllegalArgumentException("illegal use of " + MARKER + " in " + seg);
                     } else {
-                        suffix = Paths.get(seg.substring(markEnd + 1));
+                        suffix = getPath(seg.substring(markEnd + 1));
                     }
                     add(map, prefix, suffix);
                 }
@@ -1331,13 +1342,13 @@
     }
 
     private class SystemModulesLocationHandler extends BasicLocationHandler {
-        private Path javaHome;
+        private Path systemJavaHome;
         private Path modules;
         private Map<String, ModuleLocationHandler> systemModules;
 
         SystemModulesLocationHandler() {
             super(StandardLocation.SYSTEM_MODULES, Option.SYSTEM);
-            javaHome = Paths.get(System.getProperty("java.home"));
+            systemJavaHome = Locations.javaHome;
         }
 
         @Override
@@ -1347,11 +1358,11 @@
             }
 
             if (value == null) {
-                javaHome = Paths.get(System.getProperty("java.home"));
+                systemJavaHome = Locations.javaHome;
             } else if (value.equals("none")) {
-                javaHome = null;
+                systemJavaHome = null;
             } else {
-                update(Paths.get(value));
+                update(getPath(value));
             }
 
             modules = null;
@@ -1360,13 +1371,13 @@
 
         @Override
         Collection<Path> getPaths() {
-            return (javaHome == null) ? null : Collections.singleton(javaHome);
+            return (systemJavaHome == null) ? null : Collections.singleton(systemJavaHome);
         }
 
         @Override
         void setPaths(Iterable<? extends Path> files) throws IOException {
             if (files == null) {
-                javaHome = null;
+                systemJavaHome = null;
             } else {
                 Iterator<? extends Path> pathIter = files.iterator();
                 if (!pathIter.hasNext()) {
@@ -1386,16 +1397,15 @@
         }
 
         private void update(Path p) {
-            if (!isCurrentPlatform(p) && !Files.exists(p.resolve("jrt-fs.jar")) && !Files.exists(javaHome.resolve("modules")))
+            if (!isCurrentPlatform(p) && !Files.exists(p.resolve("jrt-fs.jar")) && !Files.exists(systemJavaHome.resolve("modules")))
                 throw new IllegalArgumentException(p.toString());
-            javaHome = p;
+            systemJavaHome = p;
             modules = null;
         }
 
         private boolean isCurrentPlatform(Path p) {
-            Path jh = Paths.get(System.getProperty("java.home"));
             try {
-                return Files.isSameFile(p, jh);
+                return Files.isSameFile(p, Locations.javaHome);
             } catch (IOException ex) {
                 throw new IllegalArgumentException(p.toString(), ex);
             }
@@ -1421,7 +1431,7 @@
                 return;
             }
 
-            if (javaHome == null) {
+            if (systemJavaHome == null) {
                 systemModules = Collections.emptyMap();
                 return;
             }
@@ -1431,15 +1441,15 @@
                     URI jrtURI = URI.create("jrt:/");
                     FileSystem jrtfs;
 
-                    if (isCurrentPlatform(javaHome)) {
+                    if (isCurrentPlatform(systemJavaHome)) {
                         jrtfs = FileSystems.getFileSystem(jrtURI);
                     } else {
                         try {
                             Map<String, String> attrMap =
-                                    Collections.singletonMap("java.home", javaHome.toString());
+                                    Collections.singletonMap("java.home", systemJavaHome.toString());
                             jrtfs = FileSystems.newFileSystem(jrtURI, attrMap);
                         } catch (ProviderNotFoundException ex) {
-                            URL javaHomeURL = javaHome.resolve("jrt-fs.jar").toUri().toURL();
+                            URL javaHomeURL = systemJavaHome.resolve("jrt-fs.jar").toUri().toURL();
                             ClassLoader currentLoader = Locations.class.getClassLoader();
                             URLClassLoader fsLoader =
                                     new URLClassLoader(new URL[] {javaHomeURL}, currentLoader);
@@ -1454,7 +1464,7 @@
 
                     modules = jrtfs.getPath("/modules");
                 } catch (FileSystemNotFoundException | ProviderNotFoundException e) {
-                    modules = javaHome.resolve("modules");
+                    modules = systemJavaHome.resolve("modules");
                     if (!Files.exists(modules))
                         throw new IOException("can't find system classes", e);
                 }

--- a/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/file/PathFileObject.java	Wed May 11 20:28:22 2016 +0000
+++ b/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/file/PathFileObject.java	Thu May 12 11:36:08 2016 -0700
@@ -109,7 +109,7 @@
         private DirectoryFileObject(BaseFileManager fileManager, Path path,
                 Path userPackageRootDir, RelativePath relativePath) {
             super(fileManager, path);
-            this.userPackageRootDir = userPackageRootDir;
+            this.userPackageRootDir = Objects.requireNonNull(userPackageRootDir);
             this.relativePath = relativePath;
         }
 

--- a/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/file/RelativePath.java	Wed May 11 20:28:22 2016 +0000
+++ b/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/file/RelativePath.java	Thu May 12 11:36:08 2016 -0700
@@ -26,10 +26,8 @@
 package com.sun.tools.javac.file;
 
 import java.nio.file.FileSystem;
-import java.nio.file.FileSystems;
 import java.nio.file.InvalidPathException;
 import java.nio.file.Path;
-import java.nio.file.Paths;
 import java.util.zip.ZipEntry;
 import java.util.zip.ZipFile;
 
@@ -58,13 +56,8 @@
     public abstract String basename();
 
     public Path resolveAgainst(Path directory) throws /*unchecked*/ InvalidPathException {
-        if (directory == null) {
-            String sep = FileSystems.getDefault().getSeparator();
-            return Paths.get(path.replace("/", sep));
-        } else {
-            String sep = directory.getFileSystem().getSeparator();
-            return directory.resolve(path.replace("/", sep));
-        }
+        String sep = directory.getFileSystem().getSeparator();
+        return directory.resolve(path.replace("/", sep));
     }
 
     public Path resolveAgainst(FileSystem fs) throws /*unchecked*/ InvalidPathException {

--- a/langtools/src/jdk.jshell/share/classes/jdk/jshell/SourceCodeAnalysisImpl.java	Wed May 11 20:28:22 2016 +0000
+++ b/langtools/src/jdk.jshell/share/classes/jdk/jshell/SourceCodeAnalysisImpl.java	Thu May 12 11:36:08 2016 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2015, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2014, 2016, 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
@@ -1045,7 +1045,7 @@
 
         public SourceCache(AnalyzeTask originalTask) {
             this.originalTask = originalTask;
-            Iterable<? extends Path> sources = findSources();
+            List<Path> sources = findSources();
             if (sources.iterator().hasNext()) {
                 StandardJavaFileManager fm = compiler.getStandardFileManager(null, null, null);
                 try {
@@ -1145,9 +1145,9 @@
         }
     }
 
-    private Iterable<? extends Path> availableSources;
+    private List<Path> availableSources;
 
-    private Iterable<? extends Path> findSources() {
+    private List<Path> findSources() {
         if (availableSources != null) {
             return availableSources;
         }