Java Glossary : Last Modified Date

Java definitions: 0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

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Last Modified Date

The Java spec says you cannot trust the value of File.lastModified to have any particular representation. It turns out it can be trusted after all, though it only became official with JDK 1.2. Even on Win95 it returns the number of milliseconds since 1970 Jan 01, 00:00 GMT.

With Java 1.4 you can now set the date as well with File.setLastModified ( long timestamp )

I have written native code for windows that lets you set three of the file dates. Email me if you are interested.

import com.mindprod.untouch;
/**
* Set TimeStamps on a file.
*
* @param filename Name of file to change dates on.
* @param whenFileCreated
*   timestamp milliseconds since 1970 GMT.
*   Date the file was created.
*   0 means leave as is.
* @param whenFileLastAccessed
*   timestamp milliseconds since 1970 GMT.
*   Date the file was last read.
*   0 means leave as is.
*
* @param whenFileLastUpdated
*   timestamp milliseconds since 1970 GMT.
*   Date the file was last written.
*   0 means leave as is.
*
* @return return true if all went ok
*/
public static boolean setFileTimes ( String filename ,
                                     long whenFileCreated,
                                     long whenFileLastAccessed ,
                                     long whenFileLastUpdated );

You can examine the date with File.lastModified() and set it in Java 1.4+ with File.setLastModified()

BigDate to see how you might convert these to dates and times

but you cannot get or set the creater or lastAccessed dates without without native code.

automatic file updater ¤ Delta creator student project ¤ File

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