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

BufferedOutputStream class is used to create such buffered output stream using which a chunk of bytes stored in the local buffer of BufferedOutputStream, is written out to a file.

Constructors :

BufferedOutputStream(OutputStream os)
This constructor creates a BufferedOutputStream object to write a chunk of byte to a file, which is accessed by an OutputStream.

File file= new File("D:/Textbook.txt");
FileOutputStream fos= new FileOutputStream(file);
BufferedOutputStream fis= new BufferedOutputStream(fos);
This example has created a BufferedOutputStream object to write the bytes stored in its local buffer to a file D:/Textbook.txt through OutputStream i.e. FileOutputStream, passed to constructor.

Point to remember

FileOutputStream is a subclass of OutputStream

Methods for writing using BufferedOutputStream

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

Methods Description
This method flushes any buffered data to be written out of this output stream.
write(int b)
This method writes one byte at a time to this output stream.

This method writes a whole byte array at a time to this output stream.

This method closes this outut stream and also frees any resources connected with this output stream.


Program to write to a file using BufferedOutputStream.

In this code, we are creating a BufferedOutputStream object to write the bytes stored in its local buffer to a file D:/Textbook.txt through OutputStream i.e. FileOutputStream.
//Program to create a BufferedIOutputStream to write(one byte at a time) out to an existing file.

class A
public static void main(String... ar)

String str="Java is the best programming language";
byte b[]=str.getBytes();

FileOutputStream fos= new FileOutputStream("D://TextBook.txt");
BufferedOutputStream bos= new BufferedOutputStream(fos); ///A local buffer is created which is big-
							//enough to hold a chunk of bytes to be
							//written out to a file TextBook.txt
bos.write(b); //writes to local buffer
catch(IOException e)


Output is -:

A file called "TextBook.txt" is created in D: drive, with the contents -:
Java is the best programming language

Program Analysis

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