MemoList

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.IOException;
import java.io.Writer;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class MemoList {
  public static void main(String[] args) {
    MemoList memo =
      new MemoList(args.length == 1 ? args[0] : "memo");
    while (true) {
      System.out.print("> コマンドを入力してください: ");
      String command = memo.in.nextLine();
      if (command.equals("list")) memo.list();
      else if (command.equals("add")) memo.add();
      else if (command.equals("del")) memo.delete();
      else if (command.equals("upd")) memo.update();
      else if (command.equals("save")) memo.save();
      else if (command.equals("h")) memo.help();
      else if (command.equals("q")) break;
      else memo.help();
    }
    memo.in.close();
  }
  private final List<String> memolist;
  public Scanner in;
  private final File file;

  public MemoList(String file_name) {
    file = new File(file_name);
    Scanner fin = null;
    try {
      fin = new Scanner(file);
    }
    catch (FileNotFoundException e) {
      System.err.println("File Not Found");
      System.exit(1);
    }
    memolist = new ArrayList<String>();
    while (fin.hasNextLine())
      memolist.add(fin.nextLine());
    fin.close();
    in = new Scanner(System.in);
  }

  private void add() {
    if (memolist.size() >= 10) {
      System.err.println("メモがいっぱいです");
      return;
    }
    System.out.print("> メモ: ");
    String new_memo = in.nextLine();
    memolist.add(new_memo);
  }

  private void delete() {
    System.out.print("> 番号: ");
    int index = Integer.parseInt(in.nextLine());
    if (index < 1 || index > memolist.size() + 1) return;
    memolist.remove(index - 1);
  }

  private void help() {
    System.out.println("list, add, del, upd, save, h, q");
  }

  private void list() {
    int i = 1;
    for (String e: memolist)
      System.out.println(i++ + ": " + e);
  }

  private void save() {
    Writer out = null;
    try {
      out = new FileWriter(file);
    }
    catch (IOException e) {
      System.err.println(file + "can't open");
      System.exit(1);
    }
    for (String e: memolist) {
      try {
        out.write(e + "\n");
      }
      catch (IOException e1) {
        System.err.println(file + "can't write");
        System.exit(1);
      }
    }
    try {
      out.close();
    }
    catch (IOException e1) {
      e1.printStackTrace();
    }
  }

  private void update() {
    System.out.print("> 番号: ");
    int index = Integer.parseInt(in.nextLine());
    if (index < 1 || index > memolist.size() + 1) return;
    memolist.remove(index - 1);
    System.out.print("> メモ: ");
    String new_memo = in.nextLine();
    memolist.add(index - 1, new_memo);
  }
}