Java.io.PipedReader Class in Java

This class is basically a piped character-input streams.In I/O Piped, simply means a link between two threads running in JVM at the same time. So, Pipes are used both as source or destination.
A pipe is said to be broken if a thread that was providing data bytes to the connected piped output stream is no longer alive.

Declaration:

public class PipedReader
  extends Reader

Constructor :

PipedReader() : creates a PipedReader(), that it is not connected.
PipedReader(int pSize) : creates a PipedReader, that it is not connected with specified pipe size.
PipedReader(PipedWriterStream src) : creates a PipedReader, that it is connected to PipedWriterStream – ‘src’.
PipedReader(PipedWriterStream src, int pSize) : creates a Piped Reader that is connected to Piped Writer with the specified pipe size.

Methods:

read() : java.io.PipedReader.read() reads the next character from PipedReader. This method blocks until characters are available. Returns -1 if end of the stream is detected, or an exception is thrown and the method blocks
Syntax() :

public int read()
Parameters: 
-----------
Return :
reads the next character from PipedReader.
else, return-1 if end of the stream is detected.
Exception : 
-> IOException : if in case an IO error occurs.

Implementation:

// Java program illustrating the working of read() method 
  
import java.io.*; 
public class NewClass 
{ 
    public static void main(String[] args) throws IOException 
    { 
        PipedReader geek_reader = new PipedReader(); 
        PipedWriter geek_writer = new PipedWriter(); 
          
            geek_reader.connect(geek_writer); 
  
            // Use of read() method  
            geek_writer.write(71); 
            System.out.println("using read() : " + (char)geek_reader.read()); 
            geek_writer.write(69); 
            System.out.println("using read() : " + (char)geek_reader.read()); 
            geek_writer.write(75); 
            System.out.println("using read() : " + (char)geek_reader.read());         
    } 
} 

Output :

using read() : G
using read() : E
using read() : K

read(char[] carray, int offset, int maxlen) : java.io.PipedReader.read(char[] carray, int offset, int maxlen) reads upto maxlen character from PipedReader Stream to the character array. The method blocks if end of Stream is reached or exception is thrown.
Syntax :

public int read(char[] carray, int offset, int maxlen)
Parameters : 
carray : buffer into which the data is to be read
offset : starting in the destination array - 'carray'.
maxlen : maximum length of array to be read
Return :                                               
next 'maxlen' bytes of the data as an integer value 
return -1 is end of stream is reached
Exception :
-> IOException : if in case IO error occurs.

close() : java.io.PipedPipedReader.close() closes the PipedReader Stream and releases the allocated resources.
Syntax :

public void close()
Parameters : 
--------------
Return :                                               
void
Exception :
-> IOException : if in case IO error occurs.

connect(PipedWriter source) : java.io.PipedReader.connect(PipedWriter source) connects the PipedReader to the ‘source’ Piped Writer and in case ‘source’ is pipes with some other stream, IO exception is thrown
Syntax :

public void connect(PipedWriter source)
Parameters : 
source : the PipedWriter to be connected to
Return :                                               
void
Exception :
-> IOException : if in case IO error occurs.

ready() : java.io.PipedPipedReader.ready() tells whether the stream is ready to be read or not
Syntax :

public boolean ready()
Parameters : 
--------------
Return :                                               
true : if the stream is ready to be read else, false
Exception :
-> IOException : if in case IO error occurs.

Java program illustrating the working of PipedReader class methods :

// Java program illustrating the working of PipedReader 
// connect(), read(char[] carray, int offset, int maxlen), 
// close(), ready() 
  
import java.io.*; 
public class NewClass 
{ 
    public static void main(String[] args) throws IOException 
    { 
        PipedReader geek_reader = new PipedReader(); 
        PipedWriter geek_writer = new PipedWriter(); 
  
        // Use of connect() : connecting geek_reader with geek_writer 
        geek_reader.connect(geek_writer); 
  
        geek_writer.write(71); 
        geek_writer.write(69); 
        geek_writer.write(69); 
        geek_writer.write(75); 
        geek_writer.write(83); 
  
        // Use of ready() method 
        System.out.print("Stream is ready to be read : "+geek_reader.ready()); 
  
        // Use of read(char[] carray, int offset, int maxlen) 
        System.out.print("\nUse of read(carray, offset, maxlen) : "); 
        char[] carray = new char[5]; 
        geek_reader.read(carray, 0, 5); 
  
        for (int i = 0; i < 5; i++) 
        { 
            System.out.print(carray[i]); 
        } 
  
        // USe of close() method : 
        System.out.println("\nClosing the stream"); 
        geek_reader.close(); 
    } 
} 

Output :

Stream is ready to be read : true
Use of read(carray, offset, maxlen) : GEEKS
Closing the stream

Next Article: Java.io.PipedWriter Class in Java

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