Java

Hey Guys, I am making a TicTacToe Game in Java and I am having someone difficulty figuring out what I am doing Wrong. 

1. I made a tic tic toe board which look something like this. 
Hide   Copy Code
      System.out.println("          |          |          );
      System.out.println(    0      |    1     |     2    );
      System.out.println(           |          |          );
      System.out.println(  -------------------------------);
      System.out.println(           |          |          );
      System.out.println(    3      |    4     |     5    );
      System.out.println(           |          |          );
      System.out.println(  -------------------------------);
      System.out.println(           |          |          );
      System.out.println(    6      |    7     |     8    );
      System.out.println(           |          |          );

2. I asked the user for a number between 0-8 and the number they choose will be Replaced by X.

Say they choose number 5. This is how it will look like. 


Hide   Copy Code
System.out.println("          |          |          );
System.out.println(    0      |    1     |     2    );
System.out.println(           |          |          );
System.out.println(  -------------------------------);
System.out.println(           |          |          );
System.out.println(    3      |    4     |     X    );
System.out.println(           |          |          );
System.out.println(  -------------------------------);
System.out.println(           |          |          );
System.out.println(    6      |    7     |     8    );
System.out.println(           |          |          );


3. I don't know how to create a loop which will keep asking the user for a number until it reaches to all the 8 numbers. Also, how do I check if the number is taken or not. 


IT WILL BE GREAT IF YOU CAN HELP ME.