src/java.base/share/classes/java/nio/file/Path.java

*** 1,7 ****
  /*
!  * Copyright (c) 2007, 2013, 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.  Oracle designates this
--- 1,7 ----
  /*
!  * Copyright (c) 2007, 2018, 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.  Oracle designates this
*** 43,56 ****
   * The other name elements are directory names. A {@code Path} can represent a
   * root, a root and a sequence of names, or simply one or more name elements.
   * A {@code Path} is considered to be an <i>empty path</i> if it consists
   * solely of one name element that is empty. Accessing a file using an
   * <i>empty path</i> is equivalent to accessing the default directory of the
!  * file system. {@code Path} defines the {@link #getFileName() getFileName},
!  * {@link #getParent getParent}, {@link #getRoot getRoot}, and {@link #subpath
!  * subpath} methods to access the path components or a subsequence of its name
!  * elements.
   *
   * <p> In addition to accessing the components of a path, a {@code Path} also
   * defines the {@link #resolve(Path) resolve} and {@link #resolveSibling(Path)
   * resolveSibling} methods to combine paths. The {@link #relativize relativize}
   * method that can be used to construct a relative path between two paths.
--- 43,59 ----
   * The other name elements are directory names. A {@code Path} can represent a
   * root, a root and a sequence of names, or simply one or more name elements.
   * A {@code Path} is considered to be an <i>empty path</i> if it consists
   * solely of one name element that is empty. Accessing a file using an
   * <i>empty path</i> is equivalent to accessing the default directory of the
!  * file system. The <em>extension</em> of a {@code Path} is defined to be the
!  * portion of the path after but not including the last dot ({@code '.'}) and
!  * is part of the name element farthest from the root. {@code Path} defines the
!  * {@link #getFileName() getFileName}, {@link #getParent getParent},
!  * {@link #getRoot getRoot}, {@link #getExtension getExtension}, and
!  * {@link #subpath subpath} methods to access the path components or a
!  * subsequence of its name elements.
   *
   * <p> In addition to accessing the components of a path, a {@code Path} also
   * defines the {@link #resolve(Path) resolve} and {@link #resolveSibling(Path)
   * resolveSibling} methods to combine paths. The {@link #relativize relativize}
   * method that can be used to construct a relative path between two paths.
*** 159,168 ****
--- 162,201 ----
       * @return  a path representing the path's parent
       */
      Path getParent();
  
      /**
+      * Returns the extension of this {@code Path} as a {@code String}.
+      * The extension is that portion of the path after the last dot
+      * ({@code '.'}).  If this path is empty, does not contain a dot, ends
+      * with a dot, or has a {@link FileSystem#getSeparator() name-separator}
+      * after the last dot, then this method returns an empty {@code String}.
+      *
+      * @implSpec
+      * For the cases where a non-empty string would be returned, the default
+      * implementation is equivalent for this path to:
+      * <pre>{@code
+      *     toString().substring(toString().lastIndexOf(".") + 1);
+      * }</pre>
+      *
+      * @return  the extension of this path or an empty {@code String}
+      *
+      * @since 11
+      */
+     default String getExtension() {
+         String path = toString();
+ 
+         int lastDot = path.lastIndexOf(".");
+         if (lastDot == -1 || lastDot == path.length() - 1 ||
+             path.indexOf(getFileSystem().getSeparator(), lastDot + 1) != -1) {
+             return "";
+         }
+ 
+         return path.substring(lastDot + 1);
+     }
+ 
+     /**
       * Returns the number of name elements in the path.
       *
       * @return  the number of elements in the path, or {@code 0} if this path
       *          only represents a root component
       */