Java Tutorial/File/DataOutputStream

Create DataOutputStream from BufferedOutputStream

   <source lang="java">

import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; public class MainClass {

 public static void main(String[] args) throws IOException {
   DataOutputStream out2 = new DataOutputStream(new BufferedOutputStream(new FileOutputStream(
       "Data.txt")));
   out2.writeDouble(3.14159);
   out2.writeUTF("Square root of 2");
   out2.close();
   DataInputStream in5 = new DataInputStream(new BufferedInputStream(new FileInputStream(
       "Data.txt")));
   System.out.println(in5.readDouble());
   System.out.println(in5.readUTF());
 }

}</source>

Create DataOutputStream from ByteArrayOutputStream

   <source lang="java">

import java.io.ByteArrayOutputStream; import java.io.DataOutputStream; import java.io.FileOutputStream; import java.io.IOException; public class MainClass {

 public static void main(String args[]) throws IOException {
   int howMany = 20;
   // To avoid resizing the buffer, calculate the size of the
   // byte array in advance.
   ByteArrayOutputStream bout = new ByteArrayOutputStream(howMany * 4);
   DataOutputStream dout = new DataOutputStream(bout);
   for (int i = 0; i <= 20; i++) {
     dout.writeInt(i);
   }
   FileOutputStream fout = new FileOutputStream("fibonacci.dat");
   try {
     bout.writeTo(fout);
     fout.flush();
   } finally {
     fout.close();
   }
 }

}</source>

DataOutputStream and DataInputStream: write and read primitive data type to a file

   <source lang="java">

import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.FileInputStream; import java.io.FileOutputStream; public class Main {

 public static void main(String[] args) throws Exception{
   int idA = 1;
   String nameA = "City";
   int populationA = 5;
   float tempA = 1.0f;
   int idB = 2;
   String nameB = "S";
   int populationB = 2;
   float tempB = 1.45f;
   FileOutputStream fos = new FileOutputStream("cities.dat");
   DataOutputStream dos = new DataOutputStream(fos);
   dos.writeInt(idA);
   dos.writeUTF(nameA);
   dos.writeInt(populationA);
   dos.writeFloat(tempA);
   dos.writeInt(idB);
   dos.writeUTF(nameB);
   dos.writeInt(populationB);
   dos.writeFloat(tempB);
   dos.flush();
   dos.close();
   FileInputStream fis = new FileInputStream("cities.dat");
   DataInputStream dis = new DataInputStream(fis);
   int cityId = dis.readInt();
   System.out.println("City Id: " + cityId);
   String cityName = dis.readUTF();
   System.out.println("City Name: " + cityName);
   int cityPopulation = dis.readInt();
   System.out.println("City Population: " + cityPopulation);
   float cityTemperature = dis.readFloat();
   System.out.println("City Temperature: " + cityTemperature);
 }

}</source>

Determine number of bytes written to DataOutputStream

   <source lang="java">

import java.io.DataOutputStream; import java.io.FileOutputStream; public class Main {

 public static void main(String[] args) throws Exception {
   FileOutputStream fos = new FileOutputStream("C:/Bytes.txt");
   DataOutputStream dos = new DataOutputStream(fos);
   dos.writeBytes("this is a test");
   int bytesWritten = dos.size();
   System.out.println("Total " + bytesWritten + " bytes are written to stream.");
   dos.close();
 }

}</source>

Flush output stream

   <source lang="java">

import java.io.DataOutputStream; import java.io.FileOutputStream; public class Main {

 public static void main(String[] args) throws Exception {
   FileOutputStream fos = new FileOutputStream("C:/WriteByte.txt");
   DataOutputStream dos = new DataOutputStream(fos);
   dos.writeBytes("this is a test");
   dos.flush();
   dos.close();
 }

}</source>

Write boolean to a file using DataOutputStream

   <source lang="java">

import java.io.DataOutputStream; import java.io.FileOutputStream; public class Main {

 public static void main(String[] args) throws Exception {
   FileOutputStream fos = new FileOutputStream("C:/WriteBoolean.txt");
   DataOutputStream dos = new DataOutputStream(fos);
   boolean b = false;
   dos.writeBoolean(b);
   dos.close();
 }

}</source>

Write byte to a file using DataOutputStream

   <source lang="java">

import java.io.DataOutputStream; import java.io.FileOutputStream; public class Main {

 public static void main(String[] args) throws Exception {
   FileOutputStream fos = new FileOutputStream("C:/WriteByte.txt");
   DataOutputStream dos = new DataOutputStream(fos);
   int i = 1;
   dos.writeByte(i);
   dos.close();
 }

}</source>

Write char to a file using DataOutputStream

   <source lang="java">

import java.io.DataOutputStream; import java.io.FileOutputStream; public class Main {

 public static void main(String[] args) throws Exception {
   FileOutputStream fos = new FileOutputStream("C:/WriteChar.txt");
   DataOutputStream dos = new DataOutputStream(fos);
   int ch = 65;
   dos.writeChar(ch);
   dos.close();
 }

}</source>

Write double and UTF string using DataOutputStream with BufferedOutputStream backended

   <source lang="java">

import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; public class MainClass {

 public static void main(String[] args) throws IOException {
   DataOutputStream out2 = new DataOutputStream(new BufferedOutputStream(new FileOutputStream(
       "Data.txt")));
   out2.writeDouble(3.14159);
   out2.writeUTF("Square root of 2");
   out2.close();
   DataInputStream in5 = new DataInputStream(new BufferedInputStream(new FileInputStream(
       "Data.txt")));
   System.out.println(in5.readDouble());
   System.out.println(in5.readUTF());
 }

}</source>

Write float to a file using DataOutputStream

   <source lang="java">

import java.io.DataOutputStream; import java.io.FileOutputStream; public class Main {

 public static void main(String[] args) throws Exception {
   FileOutputStream fos = new FileOutputStream("C:/WriteFloat.txt");
   DataOutputStream dos = new DataOutputStream(fos);
   float f = 5.314f;
   dos.writeFloat(f);
   dos.close();
 }

}</source>

Write integers using DataOutputStream

   <source lang="java">

import java.io.BufferedOutputStream; import java.io.DataOutputStream; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; public class MainClass {

 public static void main(String[] args) throws IOException {
   DataOutputStream dos = new DataOutputStream(new BufferedOutputStream(new FileOutputStream(
       new File("temp.tmp"))));
   for (int i = 0; i < 10; i++)
     dos.writeInt(i);
   dos.close();
 }

}</source>

Write int to a file using DataOutputStream

   <source lang="java">

import java.io.DataOutputStream; import java.io.FileOutputStream; public class Main {

 public static void main(String[] args) throws Exception{
   FileOutputStream fos = new FileOutputStream("C:/Int.txt");
   DataOutputStream dos = new DataOutputStream(fos);
   int i = 100;
   dos.writeInt(i);
   dos.close();
 }

}</source>

Write long to a file using DataOutputStream

   <source lang="java">

import java.io.DataOutputStream; import java.io.FileOutputStream; public class Main {

 public static void main(String[] args) throws Exception {
   FileOutputStream fos = new FileOutputStream("C:/WriteLong.txt");
   DataOutputStream dos = new DataOutputStream(fos);
   long l = 65;
   dos.writeLong(l);
   dos.close();
 }

}</source>

Write short to a file using DataOutputStream

   <source lang="java">

import java.io.DataOutputStream; import java.io.FileOutputStream; public class Main {

 public static void main(String[] args) throws Exception {
   FileOutputStream fos = new FileOutputStream("C:/WriteShort.txt");
   DataOutputStream dos = new DataOutputStream(fos);
   short s = 1;
   dos.writeShort(s);
   dos.close();
 }

}</source>

Write String as bytes to a file using DataOutputStream

   <source lang="java">

import java.io.DataOutputStream; import java.io.FileOutputStream; public class Main {

 public static void main(String[] args) throws Exception {
   FileOutputStream fos = new FileOutputStream("C:/Bytes.txt");
   DataOutputStream dos = new DataOutputStream(fos);
   String str = "this is test";
   dos.writeBytes(str);
   dos.close();
 }

}</source>

Write String as characters to a file using DataOutputStream

   <source lang="java">

import java.io.DataOutputStream; import java.io.FileOutputStream; public class Main {

 public static void main(String[] args) throws Exception {
   FileOutputStream fos = new FileOutputStream("C:/Chars.txt");
   DataOutputStream dos = new DataOutputStream(fos);
   String str = "this is a test";
   dos.writeChars(str);
   dos.close();
 }

}</source>