Java - DataOutputStream

The DataOutputStream stream let you write the primitives to an output source.

Following is the constructor to create a DataOutputStream.

DataOutputStream out = DataOutputStream(OutputStream  out);

Once you have DataOutputStream object in hand, then there is a list of helper methods, which can be used to write the stream or to do other operations on the stream.

SN	Methods with Description
1	public final void write(byte[] w, int off, int len)throws IOException Writes len bytes from the specified byte array starting at point off , to the underlying stream.
2	Public final int write(byte [] b)throws IOException Writes the current number of bytes written to this data output stream. Returns the total number of bytes write into the buffer.
3	(a) public final void writeBooolean()throws IOException, (b) public final void writeByte()throws IOException, (c) public final void writeShort()throws IOException  (d) public final void writeInt()throws IOException These methods will write the specific primitive type data into the output stream as bytes.
4	Public void flush()throws IOException Flushes the data output stream.
5	public final void writeBytes(String s) throws IOException Writes out the string to the underlying output stream as a sequence of bytes. Each character in the string is written out, in sequence, by discarding its high eight bits.

Example:

Following is the example to demonstrate DataInputStream and DataInputStream. This example reads 5 lines given in a file test.txt and converts those lines into capital letters and finally copies them into another file test1.txt.

import java.io.*;

public class DataInput_Stream{

   public static void main(String args[])throws IOException{
      
      //writing string to a file encoded as modified UTF-8 
      DataOutputStream dataOut = new DataOutputStream(new FileOutputStream("E:\\file.txt"));
      dataOut.writeUTF("hello");      
      
      //Reading data from the same file
      DataInputStream dataIn = new DataInputStream(new FileInputStream("E:\\file.txt"));       
      
      while(dataIn.available()>0){
      
         String k = dataIn.readUTF();
         System.out.print(k+" ");
      }
      
   }

}

Here is the sample run of the above program:

THIS IS TEST 1  ,
THIS IS TEST 2  ,
THIS IS TEST 3  ,
THIS IS TEST 4  ,
THIS IS TEST 5  ,