Why is this loop a sentinel-controlled loop?

A good answer might be:

The sentinel value "n" terminates the loop.


Reading in x

Here is the program, with some work done on reading a value for "x". (Look in Chapter 11 to review floating point input.)

import java.io.*;

class evalPoly
{
  public static void main (String[] args ) throws IOException
  {
    BufferedReader userin =  
        new BufferedReader(new InputStreamReader(System.in) );

    String xChars;                 // character version of x, from the user    
    double x;                      // a value to use with the polynomial
    String response = "y";         // "y" or "n"

    while ( response.equals( "y" ) )    
    {
       // Get a value for x.

       __________________________________________ ;

       __________________________________________ ;

       // convert data in character form to floating point form 
       x = Double.parseDouble( xChars ); 

       // Evaluate the polynomial.

       // Print out the result.

       // Ask the user if the program should continue.
       System.out.println("continue (y or n)?");

       response = userin.readLine();      
    }

  }
}

QUESTION 18:

Fill in the two blanks.