import java.io.*;

class ReadBytesFromFile {
    public static void main(String args[]) throws Exception {
        File file;
        FileInputStream fileStream = new FileInputStream(file = new File("test.txt"));

        byte[] arr = new byte[(int) file.length()];

        //чтение
        fileStream.read(arr, 0, arr.length);

        //вывод
        for (int X : arr) {
            System.out.print((char) X);
        }
    }
}