/* From: "COMPUTATIONAL PHYSICS, 2nd Ed" 
   by RH Landau, MJ Paez, and CC Bordeianu 
   Copyright Wiley-VCH, 2007.
   Electronic Materials copyright: R Landau, Oregon State Univ, 2007;
   MJ Paez, Univ Antioquia, 2007; and CC Bordeianu, Univ Bucharest, 2007.
   Support by National Science Foundation                              
*/
// AreaIO.java:  Sample IO with files

import java.io.*;                               // Import I/O library
import java.util.*;                      // Location of Scanner class

public class AreaIO  {
  public static final double PI = 3.141593;              // Constants
  
	public static void main(String[] argv) throws 
                               IOException, FileNotFoundException {
																 
    double r, A;                                 // declare variables
		
    System.out.printf("Enter name & r in Name.dat\n");    // Printout
    Scanner sc = new Scanner(new File("Name.dat"));      // Open file
    System.out.printf( "Hi %s\n", sc.next() );      // In, out line 1
    r = sc.nextDouble();                             // Read 2nd line
    System.out.printf("r = %5.3f\n",r);             // Print 2nd line
		                                                // Do computation
    A = PI * r * r;                                          
    System.out.printf("Done, look in A.dat\n");       // Screen print
    PrintWriter q=new PrintWriter(new FileOutputStream("A.dat"),true);
    q.printf("r = %5.3f\n" ,r);                        // File output
    q.printf("A = %8.1f",A);   
  }
}