// File: IO20.java (Module 13)
//
// Author: Rahul Simha
// Created: Nov 28, 1998
//
// Writing and reading raw data

import java.io.*;

// The familiar Person class.

class Person {
    String name;
    int age;

    public Person (String name, int age)
    {
	this.age = age;

	// Make sure the length is exactly five.
	if (name.length() > 5)
	    this.name = name.substring (0,5);
	else {
	    this.name = name;
	    for (int i=name.length()+1; i<=5; i++)
		this.name = this.name + " ";
	}
    }

    public String toString ()
    {
	return "Person: name=" + name + ", age=" + age;
    }

}

public class IO20 {

    public static void main (String[] argv)
    {
	try {
	    // Writing using DataInputStream.
	    FileOutputStream fileOut = new FileOutputStream ("Persons.data");
	    DataOutputStream dos = new DataOutputStream (fileOut);

	    // Create three Person instances.
	    Person p = new Person ("aaa", 16);
	    System.out.println ("Write: " + p);
	    dos.writeChars (p.name);
	    dos.writeInt (p.age);

	    p = new Person ("bbbb", 32);
	    System.out.println ("Write: " + p);
	    dos.writeChars (p.name);
	    dos.writeInt (p.age);

	    p = new Person ("cccccccc", 64);
	    System.out.println ("Write: " + p);
	    dos.writeChars (p.name);
	    dos.writeInt (p.age);

	    dos.close ();

	    // First, let's look at the raw data in the file.
	    FileInputStream fis = new FileInputStream ("Persons.data");
	    int k = fis.read();
	    int count = 1;
	    while (k >= 0) {
		byte b = (byte) k;
		String hex = Integer.toHexString (b);
		System.out.println ("Byte #" + count + ": " + hex);
		count ++;
		k = fis.read();
	    }
	    fis.close();

	    // Now read in the data.
	    fis = new FileInputStream ("Persons.data");
	    DataInputStream dis = new DataInputStream (fis);

	    char[] nameArray = new char[5];
	    for (int i=0; i<5; i++)
		nameArray[i] = dis.readChar();
	    String name = new String (nameArray);
	    int age = dis.readInt();
	    System.out.println ("Read: name=" + name + ", age=" + age);

	    nameArray = new char[5];
	    for (int i=0; i<5; i++)
		nameArray[i] = dis.readChar();
	    name = new String (nameArray);
	    age = dis.readInt();
	    System.out.println ("Read: name=" + name + ", age=" + age);

	    dis.close();
	}
	catch (IOException e) { System.out.println (e); }
    }

}