Thread: application in java

how to create an java application which can store several user name and passwords of a user in the system of different applications such as Facebook, twitter, gmail etc and when they are call they must appear on the screen. CAN any one please help me out,,,............

import java.io.*;
import java.util.scanner;
class page
{
protected String username,password;
username=mukunda;
password=mukunda;
}
class login extends page
{
public static void main(String args[])
{
String user,pass;
Scanner sc= new Scanner(System.in);
System.out.println("username:");
user=Sc.nextLine();
System.out.println("password");
pass=Sc.nextLine();

if(user=username)
{
System.out.println("user name is correct");
if(pass=password)
{
System.out.println("password is correct");
System.out.println("login is successful");
System.out.println("--------------------);
System.out.println("enter your choice");
System.out.println("1. Facebook");
System.out.println("2. Orkut");
System.out.println("3. Twitter");
System.out.println("4. Gmail");
int choice;
choice=Sc.nextInt();
switch(case)
{
case1:
System.out.println("**FACEBOOK**);
System.out.println("user name is mukunda");
System.out.println("pass word is mukunda12345");
break;
case2:
System.out.println("**ORKUT**);
System.out.println("user name is muukunda");
System.out.println("pass word is mukunda7");
break;
case3:
System.out.println("**TWITTER**);
System.out.println("user name is mukunda");
System.out.println("pass word is mukunda6");
break;
case4:
System.out.println("**GMAIL**);
System.out.println("user name is mukunda");
System.out.println("pass word is mukunda2");
break;
defualt:
System.out.println("**invalid input**);
break;
}
}
else
System.out.println("password is incorrect");
}
else
System.out.println("incorrect user name");
}
}
}

CAN ANY ONE PLEASE CHECK THE ERRORS