Base de datos de amigos, utilizando archivos Ejercicio Java - Curso de Programación Java

import java.util.*;
public class FriendsDatabase
{
	private final static class people
	{
		public String name;
		public String email;
		public String address;
		public short year;

		public people clone()
		{
			people varCopy = new people();

			varCopy.name = this.name;
			varCopy.email = this.email;
			varCopy.address = this.address;
			varCopy.year = this.year;

			return varCopy;
		}
	}

	public static void main(String[] args)
	{
		int total = 275;
		people[] p = new people[total];
		int amount = 0;

		char option;
		boolean found;
		String textSearch;
		String name = "friends.dat";

		if ((new java.io.File(name)).isFile())
		{
			java.io.FileReader file = new java.io.FileReader(name);
			java.io.BufferedReader fileBufferedReader = new java.io.BufferedReader(file);
			amount = (int)fileBufferedReader.readLine();

			fileBufferedReader.readLine();

			for (int i = 0; i < amount; i++)
			{
				if (i < total)
				{
					p[i].name = fileBufferedReader.readLine();
					p[i].email = fileBufferedReader.readLine();
					p[i].address = fileBufferedReader.readLine();
					p[i].year = (short)fileBufferedReader.readLine();
					fileBufferedReader.readLine();
				}
			}
			file.close();
		}

		do
		{
			System.out.println("1- Add data");
			System.out.println("2- Show");
			System.out.println("3- View all data");
			System.out.println("4- Show between dates");
			System.out.println("5- Show oldest");
			System.out.println("6- Show fields match");
			System.out.println("0- Exit");

			System.out.print("Enter a option: ");
			option = (char)new Scanner(System.in).nextLine();

			switch (option)
			{

				case '1':
					if (amount < total - 1)
					{
						do
						{
							System.out.print("Name: ");
							p[amount].name = new Scanner(System.in).nextLine();

							if (p[amount].name.length() > 40)
							{
								System.out.println("Max 40 letters");
							}
						} while (p[amount].name.length() > 40);

						do
						{
							System.out.print("Email: ");
							p[amount].email = new Scanner(System.in).nextLine();

							if (p[amount].email.length() > 30)
							{
								System.out.println("Max 30 letters");
							}
						} while (p[amount].email.length() > 30);

						do
						{
							System.out.print("Address: ");
							p[amount].address = new Scanner(System.in).nextLine();

							if (p[amount].address.length() > 150)
							{
								System.out.println("Max 150 letters");
							}
						} while (p[amount].address.length() > 150);

						do
						{
							System.out.print("Year: ");
							p[amount].year = Short.parseShort(new Scanner(System.in).nextLine());

							if (p[amount].year < 1850 || p[amount].year > 2100)
							{
								System.out.println("1850-2100");
							}
						} while (p[amount].year < 1850 || p[amount].year > 2100);

						amount++;
						System.out.println();
					}
					else
					{
						System.out.println("Full");
					}

					break;

				case '2':
					if (amount == 0)
					{
						System.out.println("No data");
					}
					else
					{
						for (int i = 0; i < amount; i++)
						{
							if (p[i].name.length() <= 30)
							{
								System.out.printf("%1$s: Name = %2$s" + "\r\n", i + 1, p[i].name);
							}
							else
							{
								System.out.printf("%1$s: Name = %2$s" + "\r\n", i + 1, p[i].name.substring(0, 30) + "...");
							}

							if (i % 20 == 19)
							{
								new Scanner(System.in).nextLine();
							}
						}
					}

					break;
				case '3':
					System.out.print("Enter the person: ");
					textSearch = new Scanner(System.in).nextLine();

					found = false;
					for (int i = 0; i < amount; i++)
					{
						if (textSearch.toLowerCase().equals(p[i].name.toLowerCase()))
						{
							found = true;
							System.out.printf("%1$s: Year = %2$s, Email = %3$s, Address = %4$s" + "\r\n", i + 1, p[i].year, p[i].email, p[i].address);
						}
					}

					if (!found)
					{
						System.out.println("Not exists");
					}

					break;

				case '4':
					System.out.print("Enter the first year: ");

					int year1 = Short.parseShort(new Scanner(System.in).nextLine());

					System.out.print("Enter the second year: ");

					int year2 = Short.parseShort(new Scanner(System.in).nextLine());


					if (year1 > year2)
					{
						int aux = year2;
						year2 = year1;
						year1 = aux;
					}

					found = false;
					for (int i = 0; i < amount; i++)
					{
						if (p[i].year >= year1 && p[i].year <= year2)
						{
							System.out.print(p[i].name + " - ");
							found = true;
						}
					}

					if (!found)
					{
						System.out.println("Not found");
					}
					break;


				case '5':
					if (amount == 0)
					{
						System.out.println("No data");
					}
					else
					{
						int firstYear = p[0].year;
						found = false;

						for (int i = 1; i < amount; i++)
						{
							if (p[i].year < firstYear)
							{
								firstYear = p[i].year;
							}
						}

						for (int i = 0; i < amount; i++)
						{
							System.out.printf("%1$s: Address = %3$s, Year = %4$s" + "\r\n", i + 1, p[i].name, p[i].address, p[i].year);

							if (new Scanner(System.in).nextLine().toLowerCase().equals("end"))
							{
								break;
							}
						}
					}
					break;

				case '0':
					break;

				default:
					System.out.println("Wrong option");
					break;
			}

		} while (option != '0');

		java.io.FileWriter dataFile = new java.io.FileWriter(name);
		dataFile.write(String.valueOf(amount) + System.lineSeparator());
		dataFile.WriteLine();

		for (int i = 0; i < amount; i++)
		{
			dataFile.write(p[i].name + System.lineSeparator());
			dataFile.write(p[i].email + System.lineSeparator());
			dataFile.write(p[i].address + System.lineSeparator());
			dataFile.write(String.valueOf(p[i].year) + System.lineSeparator());
			dataFile.WriteLine();
		}

		dataFile.close();
	}
}