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()

BufferReader java file io — Fig 1: BufferReader class hierarchy

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)

java file io bufferwriter — Fig 2: BufferWriter Class hierarchy

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:

Write file bufferWriter — Fig 3: Written contents to file -BufferWriter

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

BufferReader class:

BufferWriter class:

Program – Java file IO using BufferedReader & BufferedWriter

Output – Java file IO using BufferedReader & BufferedWriter

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