/*
 * Copyright (c) 2009-2011 Oracle and/or its affiliates. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Oracle or the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

import java.io.*;
import java.nio.file.*;

public class CountLetter {
    private char lookFor;
    private Path file;

    CountLetter(char lookFor, Path file) {
        this.lookFor = lookFor;
        this.file = file;
    }

    public int count() throws IOException {
        int count = 0;
        try (InputStream in = Files.newInputStream(file);
            BufferedReader reader = new BufferedReader(new InputStreamReader(in)))
            {
            String line = null;
            while ((line = reader.readLine()) != null) {
                for (int i = 0; i < line.length(); i++) {
                    if (lookFor == line.charAt(i)) {
                        count++;
                    }
                }
            }
        } catch (IOException x) {
            System.err.println(x);
        }
        return count;
    }

    static void usage() {
        System.out.println("usage: java CountLetter <letter>");
        System.exit(-1);
    }

    public static void main(String[] args) throws IOException {

        if (args.length != 1 || args[0].length() != 1)
            usage();

        char lookFor = args[0].charAt(0);
        Path file = Paths.get("xanadu.txt");
        int count = new CountLetter(lookFor, file).count();
        System.out.format("File '%s' has %d instances of letter '%c'.%n",
                file, count, lookFor);
    }
}