Im afraid my friend, you cant get the password, if you could, then thousands of "password recovery aka password stealing" apps in java would be floating around the internet...
Windows password are stored in a file, cant recall the name, and they are encrypted, so you need
1. Read windows partition from Linux or DOS
2. Take the password file
3. Use a brute-force password recovery app, to TRY to find some of the passwords
As you can see, theres no way to read these passwords from Java or any other language, even If you could read the file on real time (you cant, windows blocks it, thats the reason of step 1 mentioned before), you would still have to try and find the password through brute force, which is, time/resources consuming, you could spend 24 hours in a row trying to get a password and either succeed or not, depending on the complexity of the password (aka, lenght, different characters, and so on..)
Hope thats clear
cheers
Unsolved 
