question: public static void copyFile ( File srcFile , File destFile ) throws IOException { if ( destFile . exists ( ) && destFile . isDirectory ( ) ) { throw new IOException ( "Destination '" + destFile + "' exists but is a directory" ) ; } FileInputStream input = new FileInputStream ( srcFile ) ; try { FileOutputStream output = new FileOutputStream ( destFile ) ; try { copy ( input , output ) ; } finally { close ( output ) ; } } finally { close ( input ) ; } if ( srcFile . length ( ) != destFile . length ( ) ) { throw new IOException ( "Failed to copy full contents from '" + srcFile + "' to '" + destFile + "'" ) ; } destFile . setLastModified ( srcFile . lastModified ( ) ) ; }
target:  Copy a file preserving the date.