BufferedReader

File Input/Output operations consume a lot of important resources and are time consuming. Hence, reading a chunk of characters out of a file and storing it in a local buffer for later processing is faster and than reading a character at a time, out of a file. Such buffering speeds up the I/O process.

BufferedReader class is used to create such buffered reader stream through which a chunk of characters are read out of a file and transferred to a local buffer for later use.

Constructors :

BufferedReader(Reader r)
This constructor creates a BufferedReader object to read characters out of a file, which is accessed by a Reader, passed to this constructor as a parameter. Example-: `File file= new File("D:/Textbook.txt"); FileReader fr= new FileReader(file); BufferedReader br= new BufferedReader(fr);`

This example has created a BufferedReader object to read characters out of a file D:/Textbook.txt using Reader i.e. FileReader. As soon as this constructor is called, a large chunk of characters are read out of file and stored in the local buffer of BufferedReader.

Point to remember

BufferedReader is a subclass of Reader class.

Methods for reading BufferedReader

Some methods that we generally use while working with BufferedReader are shown in the table below :

Methods	Description
available()	This method gives the remaining number of bytes available to read from this input character stream's buffer.
read()	This method reads one character at a time from this input character stream's buffer.
read(char[])	This method reads a whole character array at a time from this input character stream's buffer.
close()	This method closes this input stream and also frees any resources connected with this input stream.

Program to read one character a time from a file using BufferedReader.

We are creating a BufferedReader object to read characters from a file D:\\TextBook.txt, referenced by FileReader object. Let's the contents of this file are -:
Hello from Java
Next topic is BufferedWriter class

//A program to create a BufferedReader Stream for reading characters from a local buffer. 

import java.io.*;
class A
{
public static void main(String... ar)
{

try
{
File file= new File("TextBook9.txt");
FileReader fr= new FileReader(file); 
BufferedReader br = new BufferedReader(fr); //This will transfer chunk of characters 
					    //from file to buffer of BufferedReader
								
int c;

//Reading one character a time from buffer
while( (c=br.read())!=-1)      
{
System.out.print((char)c);
}

br.close();
}
catch(IOException e)
{
System.out.println(e);
}

}
}

Output is -:

Hello from Java!
Next topic is BufferedWriter class

Program Analysis

We are reading characters out of a local file(referenced a File object), using BufferedReader class.
Calling the constructor of BufferedReader fills its buffer with a chunk of characters read out of the file.
Data in buffer is read(one character a time) by calling read() method.
Finally, the opened character streams are closed by close() method to free any connected resouces.

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