I have doubt onfollowing topics Please Reply
do we ever used HashTable and Directory?
What are statements in Java?
What is the base class for all swing components?
Is there any tag in htm to upload and download files
Here again I don't know what you want/need in both #1 and #2.
The "Object" class, I suppose, can be considered the "base" class.
In HTML, to access other sites, you would utilize the "anchor" tag;
For upload/download of files on a web site you'll need to incorporate
a server-side language that performs the actual file i/o and can also,
if needed, generate your dynamic html (such as a Java servlet or,
from an applet's perspective, "RMI").
There are many others but your questions appear Java in nature so
I've included these.