Read write file using BufferedReader & BufferedWriter in java (example)

BufferWriter, writes to character based stream and BufferReader, reads from character based stream, so as to provide efficient writing/reading of characters, arrays, and strings.

BufferReader class:

BufferReader class reads text from a character based stream, read methods are as follows:

• public int read()
• public int read(char[] cbuf, int off, int len)
• public String readLine()

BufferWriter class:

BufferWriter writes text to a character based stream. Write methods are as follows:

• public void write(int c)
• public void write(char[] cbuf, int off, int len)
• public void write(String s, int off, int len)

We have discussed similar post to read & writer file in java:

• Java IO operation using BufferWriter & BufferReader (NIO).
• Java IO operations to read & write UTF contents using BufferReader/BufferWriter (without NIO).
• Read & write file contents (UTF) using InputStreamReader/OutputStreamWriter.
• Read & write contents (without UTF) using InputStreamReader/OutputStreamWriter

Program – Java file IO using BufferedReader & BufferedWriter

package org.learn.io;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;

public class BufferReaderWriter {
	public static void main(String[] args) throws IOException {		
		writeUsingBufferWriter();
		readUsingBufferReader();	
	}

	private static void writeUsingBufferWriter() throws IOException {
		System.out.println("1. Start writing contents to file - BufferedWriter");		
		try (FileOutputStream fileStream = new FileOutputStream(new File("sampleFile.txt"));
				OutputStreamWriter writer = new OutputStreamWriter(fileStream);
				BufferedWriter bufferWriter = new BufferedWriter(writer)) {
			bufferWriter.write("Soccer");
			bufferWriter.newLine();
			bufferWriter.write("Tennis");
			bufferWriter.newLine();
			bufferWriter.write("Badminton");
			bufferWriter.newLine();
			bufferWriter.write("Hockey");
			bufferWriter.newLine();
		}
		System.out.println("2. Successfully written contents to file - BufferedWriter");
	}
	
	private static void readUsingBufferReader() throws IOException {
		try (FileInputStream fileStream = new FileInputStream(new File("sampleFile.txt"));
				InputStreamReader reader = new InputStreamReader(fileStream);
				BufferedReader bufferedReader = new BufferedReader(reader)) {
			System.out.println("\n3. Start Reading file using BufferedReader");
			String line;
			while ((line = bufferedReader.readLine()) != null) {
				System.out.println(line);
			}
			System.out.println("4. End Reading file using BufferedReader");
		}
	}

}

The content of sampleFile.txt is as follows:

Output – Java file IO using BufferedReader & BufferedWriter

1. Start writing contents to file - BufferedWriter
2. Successfully written contents to file - BufferedWriter

3. Start Reading file using BufferedReader
Soccer
Tennis
Badminton
Hockey
4. End Reading file using BufferedReader