public CacheSpan touch(){
  long now=System.currentTimeMillis();
  File newCacheFile=getCacheFileName(file.getParentFile(),key,position,now);
  file.renameTo(newCacheFile);
  return CacheSpan.createCacheEntry(key,position,now,newCacheFile);
}

public CacheSpan touch ( ) { long now = System . currentTimeMillis ( ) ; File newCacheFile = getCacheFileName ( file . getParentFile ( ) , key , position , now ) ; file . renameTo ( newCacheFile ) ; return CacheSpan . createCacheEntry ( key , position , now , newCacheFile ) ; }
renames the file underlying this cache span to update its last access time .
