Question: I have tried several ways to login to a website through java. I have used watij, HTMLunit etc. but due to not so familiar with any of these, I am not able to login successfully.

Can anyone tell me in detail how to login through java

To be more specific, I want to login to the ORKUT and want the pagesource of the page that comes after login.

Answer: 
The answer depends on how the website attempts to authenticate you:

* Do you have to set a username and password in the HTTP headers (basic auth)?
* Or do you have to fill out and submit a form containing the username and password?

For either I would recommend commons-httpclient, although the latter screen-scraping approach is always messy to do programatically.

For basic authentication, take a look at httpclient's [Authentication Guide](http://hc.apache.org/httpclient-3.x/authentication.html).

For forms authentication, you'll need to check the HTML source of the page to understand 

* The URL the form is submitted to
* What the names of the parameters to submit are

For help on how to submit a form in httpclient, take a look at [the documentation on the POST method](http://hc.apache.org/httpclient-3.x/methods/post.html).

The httpclient site also contains a [basic tutorial](http://hc.apache.org/httpclient-3.x/tutorial.html).
Why are you trying to login via Java, why not just use cURL? Is there something specific you're trying to accomplish?