import Chapter2.MyInput;
import java.io.*;
public class Raf
{
   public static void main(String[] args) 
   {
      Person p = new Person();  // make an empty person
      RandomAccessFile file=null;
      try {
         file = new RandomAccessFile("person.dat", "rw"); // no append!
      } catch (Exception e) {
         System.out.println(e);
      }
      String choice=null;
      do {
         System.out.println("Enter data for a person:");
         p.getPerson();
         p.writePerson(file);
         System.out.print("Do more? (y/n): ");
         choice = MyInput.readString();
      } while(choice.equals("y"));
      try {
         System.out.println("File Size " + file.length());
      } catch (Exception e) {
         System.out.println(e);
      }
      int pnum;
      do {
         System.out.print("Enter a person number:");
         pnum = MyInput.readInt();
         p.readPerson(file, pnum);
         p.showPerson();
         System.out.print("Do more? (y/n): ");
         choice = MyInput.readString();
      } while(choice.equals("y"));
   }
}

class Person {
   private int id;
   private char grade;

   public void getPerson() {
      System.out.print("Enter id: ");
      id = MyInput.readInt();
      System.out.print("Enter grade: ");
      grade = MyInput.read1char();
   }
   public void writePerson(RandomAccessFile raf) {
      try {
         raf.writeInt(id);
         raf.writeChar(grade);
      } catch (Exception e) {
         System.out.println(e);
      }
   }
   public void readPerson(RandomAccessFile raf, int pid) {
      long pos = pid * (4+2); // 1char = 2bytes
      try {
         raf.seek(pos);
         id = raf.readInt();
         grade = raf.readChar();
      } catch (Exception e) {
         System.out.println(e);
      }
   }
   public void showPerson() {
      System.out.println("Id: " + id);
      System.out.println("Grade: " + grade);
   }
}