BufferedWriter

File Input/Output operations consume a lot of important resources and are time consuming. Hence, writing a chunk of character to a file is faster than writing one character a time. It speeds up the I/O process.

BufferedWriter class is used to create such buffered character stream using which a chunk of characters stored in the local buffer of BufferedWriter, is written out to a file.

Constructors :

BufferedWriter(Writer r)
This constructor creates a BufferedWriter object to write characters out of a file, accessed by a *Writer* Example-: `File file= new File("D:\\Textbook.txt"); FileWriter fw= new FileWriter(file); BufferedWriter bw= new BufferedWriter(fw);`

This example has created a BufferedWriter object to write characters stored in its local buffer to a file D:\\Textbook.txt through a writer character stream, FileWriter.

Point to remember

BufferedWriter is a subclass of Writer class.

Methods for writing using BufferedWriter

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

Methods	Description
flush()	This method flushes any data to be written out of this character output stream's buffer.
write(int c)	This method writes one character at a time to this character output stream's buffer.
write(char[])	This method writes a whole character array at a time to this character output stream's buffer.
write(String str)	This method writes a String to this character output stream's buffer.
newLine()	This method writes a line separator.
close()	This method closes this output stream and also frees any resources connected with this output stream.

Writing a character array and a String to a file using BufferedWriter.

In this code, we are creating a BufferedWriter object to write the characters stored in its local buffer to a file D:\\Textbook.txt through a writer character stream i.e. FileWriter.

//A program to create a buffered output Stream for writing characters.

import java.io.*;
class A
{
public static void main(String... ar)
{
char[] arr= {'H', 'e', 'l' , 'l' , 'o'};
String str="Next topic is PrintWriter";



try
{
File file= new File("TextBook9.txt");
FileWriter fw= new FileWriter(file); // This will create the file and we don't need to call createNewFile();
BufferedWriter bw = new BufferedWriter(fw);

for(char ch : arr)
bw.write(ch);	//Writing a char at a time, using for-each loop

bw.newLine();	//Writing a newline character.

bw.write(str);	////Writing a String.

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

}
}

Output is -:

After the execution of this program, a file TextBook.txt is created in the D: drive, with contents -:
Hello
Next topic is PrintWriter

Program Analysis

Calling the constructor of BufferedWriter creates its buffer, big enough to hold a chunk of characters.
Data in buffer is written(one character at a time) by calling write(int c) method, a newline character is written by calling newLine() method and a String is written by calling write(String str) method.
A chunk of characters in buffer is written to the file at once by flush() method.
Finally, the opened input streams are closed by close() method to free any connected resources.

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