Java/File Input Output/Buffer Stream

Reading from a Binary File with BufferedInputStream

 
import java.io.BufferedInputStream;
import java.io.DataInputStream;
import java.io.EOFException;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.text.NumberFormat;
public class ReadBinaryFile {
  public static void main(String[] args) throws Exception{
    NumberFormat cf = NumberFormat.getCurrencyInstance();
    File file = new File("product.dat");
    DataInputStream  in = new DataInputStream(new BufferedInputStream(new FileInputStream(file)));
    boolean eof = false;
    while (!eof) {
      Product movie = readMovie(in);
      if (movie == null)
        eof = true;
      else {
        String msg = Integer.toString(movie.year);
        msg += ": " + movie.title;
        msg += " (" + cf.format(movie.price) + ")";
        System.out.println(msg);
      }
    }
    in.close();
  }
  private static Product readMovie(DataInputStream in) {
    String title = "";
    int year = 0;
    double price = 0.0;
    try {
      title = in.readUTF();
      year = in.readInt();
      price = in.readDouble();
    } catch (EOFException e) {
      return null;
    } catch (IOException e) {
      System.out.println("I/O Error");
      System.exit(0);
    }
    return new Product(title, year, price);
  }
}
class Product {
  public String title;
  public int year;
  public double price;
  public Product(String title, int year, double price) {
    this.title = title;
    this.year = year;
    this.price = price;
  }
}

Use buffered input.

 
import java.io.BufferedInputStream;
import java.io.ByteArrayInputStream;
import java.io.IOException;
class BufferedInputStreamDemo {
  public static void main(String args[]) throws IOException {
    String s = "This is a © copyright symbol " + "but this is &copy not.\n";
    byte buf[] = s.getBytes();
    ByteArrayInputStream in = new ByteArrayInputStream(buf);
    BufferedInputStream f = new BufferedInputStream(in);
    int c;
    boolean marked = false;
    while ((c = f.read()) != -1) {
      switch (c) {
      case "&":
        if (!marked) {
          f.mark(32);
          marked = true;
        } else {
          marked = false;
        }
        break;
      case ";":
        if (marked) {
          marked = false;
          System.out.print("(c)");
        } else
          System.out.print((char) c);
        break;
      case " ":
        if (marked) {
          marked = false;
          f.reset();
          System.out.print("&");
        } else
          System.out.print((char) c);
        break;
      default:
        if (!marked)
          System.out.print((char) c);
        break;
      }
    }
  }
}

Use BufferedInputStream and BufferedOutputStream to copy byte array

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
public class Main {
  public static void main(String[] args) throws Exception {
    String fromFileName = "from.txt";
    String toFileName = "to.txt";
    BufferedInputStream in = new BufferedInputStream(new FileInputStream(fromFileName));
    BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(toFileName));
    byte[] buff = new byte[32 * 1024];
    int len;
    while ((len = in.read(buff)) > 0)
      out.write(buff, 0, len);
    in.close();
    out.close();
  }
}

Writing to a Binary File

 
import java.io.BufferedOutputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileOutputStream;
public class WriteBinaryFile {
  public static void main(String[] args) throws Exception {
    Product[] movies = new Product[10];
    movies[0] = new Product("W", 1946, 14.95);
    movies[1] = new Product("T", 1965, 12.95);
    movies[2] = new Product("Y", 1974, 16.95);
    movies[3] = new Product("R", 1975, 11.95);
    movies[4] = new Product("S", 1977, 17.95);
    movies[5] = new Product("P", 1987, 16.95);
    movies[6] = new Product("G", 1989, 14.95);
    movies[7] = new Product("A", 1995, 19.95);
    movies[8] = new Product("Game", 1997, 14.95);
    movies[9] = new Product("F", 2001, 19.95);
    DataOutputStream out = openOutputStream("movies.dat");
    for (Product m : movies)
      writeMovie(m, out);
    out.close();
  }
  private static DataOutputStream openOutputStream(String name) throws Exception {
    DataOutputStream out = null;
    File file = new File(name);
    out = new DataOutputStream(new BufferedOutputStream(new FileOutputStream(file)));
    return out;
  }
  private static void writeMovie(Product m, DataOutputStream out) throws Exception {
    out.writeUTF(m.title);
    out.writeInt(m.year);
    out.writeDouble(m.price);
  }

}
class Product {
  public String title;
  public int year;
  public double price;
  public Product(String title, int year, double price) {
    this.title = title;
    this.year = year;
    this.price = price;
  }
}