6791812: (file spec) Incompatible File.lastModified() and setLastModified() for negative time
Summary: Amend verbiage describing return value to explain negative values.
Reviewed-by: rriggs, smarks
--- a/jdk/src/java.base/share/classes/java/io/File.java Tue Jun 13 10:44:18 2017 -0700
+++ b/jdk/src/java.base/share/classes/java/io/File.java Tue Jun 13 13:43:37 2017 -0700
@@ -916,23 +916,28 @@
* Returns the time that the file denoted by this abstract pathname was
* last modified.
*
+ * @apiNote
+ * While the unit of time of the return value is milliseconds, the
+ * granularity of the value depends on the underlying file system and may
+ * be larger. For example, some file systems use time stamps in units of
+ * seconds.
+ *
* <p> Where it is required to distinguish an I/O exception from the case
* where {@code 0L} is returned, or where several attributes of the
* same file are required at the same time, or where the time of last
* access or the creation time are required, then the {@link
* java.nio.file.Files#readAttributes(Path,Class,LinkOption[])
- * Files.readAttributes} method may be used.
- *
- * @apiNote
- * While the unit of time of the return value is milliseconds,
- * the granularity of the value depends on the underlying
- * file system and may be larger. For example, some
- * file systems use time stamps in units of seconds.
+ * Files.readAttributes} method may be used. If however only the
+ * time of last modification is required, then the
+ * {@link java.nio.file.Files#getLastModifiedTime(Path,LinkOption[])
+ * Files.getLastModifiedTime} method may be used instead.
*
* @return A <code>long</code> value representing the time the file was
* last modified, measured in milliseconds since the epoch
* (00:00:00 GMT, January 1, 1970), or <code>0L</code> if the
- * file does not exist or if an I/O error occurs
+ * file does not exist or if an I/O error occurs. The value may
+ * be negative indicating the number of milliseconds before the
+ * epoch
*
* @throws SecurityException
* If a security manager exists and its {@link