Convert Inputstream to OutputStream

This discussion shows how to convert an  InputStream to OutputStream. Here we are trying to make understand the conversion of an input stream into an output stream by taking an example. In this example we are taking a file as input stream and also creating an object of output stream. To convert an input stream into output stream we read a single character from input stream and write it into an output stream.
The class  java.io.InputStream is an abstract class which extends Object class and is a superclass of all classes that represents an input stream of byte.
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The class java.io.OutputStream is an abstract class which extends Object class. java.io.OutputStream class is superclass of all classes representing an output stream of bytes. An output stream accepts output bytes and sends the output to destination.

The class java.io.FileInputStream  is an abstract class which extends InputStream. A FileInputStream calss is used to obtain input bytes from a file in a file system.

System class contains several useful classes and methods and can never be instantiated. This class extends Object class.

Field Summary
System.err: "err" is used to display error output stream.

InputStream.in: "in" is used to tack input from input stream.

PrintStream.out: out is used for displaying the standard output stream.

The code of the program is given below:

import java.io.*; 
public class InputToOutputStream
{
   public static void main( String args[] )
throws IOException
     {
     InputStream in = new FileInputStream
( "InputToOutputStream.java" );
     OutputStream out = System.out;
     int nextChar;
     while ( ( nextChar = in.read() ) != -1  )
     out.write(  Character.toUpperCase( 
(char) nextChar ) );
     out.write( '\n' );
     out.flush();
     }
}

The output of the program is given below:

C:\rajesh\io>javac InputToOutputStream.java C:\rajesh\io>java InputToOutputStream IMPORT JAVA.IO.*; PUBLIC CLASS INPUTTOOUTPUTSTREAM { PUBLIC STATIC VOID MAIN( STRING ARGS[] )THROWS IOEXCEPTION { INPUTSTREAM IN = NEW FILEINPUTSTREAM( "INPUTTOOUTPUTSTREAM.JAVA" ); OUTPUTSTREAM OUT = SYSTEM.OUT; INT NEXTCHAR; WHILE ( ( NEXTCHAR = IN.READ() ) != -1 ) OUT.WRITE( CHARACTER.TOUPPERCASE( (CHAR) NEXTCHAR ) ); OUT.WRITE( '\N' ); OUT.FLUSH(); }}

Download this example.