Ok, text based games need lot's of loops and descision structers. I assume you know how to declare primitive data types already? Try something like this for the computer to accept input of a character, and give a response accordingly.
public class Game
{
public static void main(String[]args)throws Exception
{
System.out.println("Do you like Java? Y for yes, N for no.");
char input;
input = (char)System.in.read();
if(input.equalsIgnoreCase("y")
System.out.println("Me to!");
if(input.equalsIgnoreCase("n")
System.out.println("Too bad...");
}
}