import static java.util.function.Function.identity;
import static java.util.stream.Collectors.counting;
import static java.util.stream.Collectors.groupingBy;

import java.io.*;
import java.nio.*;
import java.util.*;
import java.nio.channels.FileChannel;
import java.util.function.Supplier;
import java.util.stream.Stream;

public class Main {
	public static void main(String... args) {
		try (RandomAccessFile f = new RandomAccessFile(new File("/tmp/wtf"), "r")) {
			long fileSize = f.length();
			MappedByteBuffer mem = f.getChannel().map(FileChannel.MapMode.READ_ONLY, 0, fileSize);
			Map<Integer, Long> freqStat =  Stream.generate(unsignedByteSupplier(mem))
												 .limit(fileSize)
												 .collect(groupingBy(identity(), counting()));
			System.out.println(freqStat);
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	static Supplier<Integer> unsignedByteSupplier(ByteBuffer buff) {
		return () -> Byte.toUnsignedInt(buff.get());
	}
}