8024695: new File("").exists() returns false whereas it is the current working directory

Reviewed-by: alanb, rriggs, lancea

src/java.base/share/classes/java/io/File.java

@@ -56,7 +56,8 @@ import jdk.internal.util.StaticProperty;
  * case of Microsoft Windows UNC pathnames, a hostname.  Each subsequent name
  * in an abstract pathname denotes a directory; the last name may denote
  * either a directory or a file.  The <em>empty</em> abstract pathname has no
- * prefix and an empty name sequence.
+ * prefix and an empty name sequence.  Accessing a file with the empty abstract
+ * pathname is equivalent to accessing the current user directory.
  *
  * <p> The conversion of a pathname string to or from an abstract pathname is
  * inherently system-dependent.  When an abstract pathname is converted into a

src/java.base/share/classes/java/io/FileSystem.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2025, 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
@@ -33,6 +33,22 @@ import java.lang.annotation.Native;
 
 abstract class FileSystem {
 
+    /* -- Current Working Directory --*/
+
+    /* lazy initialization of CWD object */
+    private static class CurrentWorkingDirectoryHolder {
+        static final File CURRENT_WORKING_DIRECTORY = currentWorkingDirectory();
+
+        private static final File currentWorkingDirectory() {
+            return new File(".");
+        }
+    }
+
+    /* CWD object accessor */
+    static File getCWD() {
+        return CurrentWorkingDirectoryHolder.CURRENT_WORKING_DIRECTORY;
+    }
+
     /* -- Normalization and construction -- */
 
     /**