File Streams: FileReader, FileWriter, BufferedReader, and BufferedWriter

Intermediate13 min read•Updated: 2026-10-22

📁 File Streams: BufferedReader and BufferedWriter

Introduction

Reading and writing text files on disk is standard for logs and persistence. While FileReader reads character-by-character from disk (slow), wrapping it in BufferedReader batches reads through an internal memory buffer for 50x faster I/O.

💻 Writing and Reading Files

1import java.io.BufferedWriter;
2import java.io.BufferedReader;
3import java.io.FileWriter;
4import java.io.FileReader;
5import java.io.IOException;
6 
7public class FileIODemo {
8    public static void main(String[] args) {
9        String filename = "students_db.csv";
10 
11        // 1. Fast writing with BufferedWriter
12        try (BufferedWriter writer = new BufferedWriter(new FileWriter(filename))) {
13            writer.write("101,Aarav Sharma,Java Intermediate\n");
14            writer.write("102,Sneha Gupta,Modern C++\n");
15            System.out.println("Records written to " + filename);
16        } catch (IOException e) {
17            e.printStackTrace();
18        }
19 
20        // 2. Fast reading line-by-line with BufferedReader
21        try (BufferedReader reader = new BufferedReader(new FileReader(filename))) {
22            String line;
23            while ((line = reader.readLine()) != null) {
24                System.out.println("Line: " + line);
25            }
26        } catch (IOException e) {
27            e.printStackTrace();
28        }
29    }
30}

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Modern Java NIO: java.nio.file.Path and java.nio.file.Files

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LinkedHashMap and TreeMap for Sorted Key-Value Pairs	Modern Java NIO: java.nio.file.Path and java.nio.file.Files

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Modern Java NIO: java.nio.file.Path and java.nio.file.Files

File Streams: FileReader, FileWriter, BufferedReader, and BufferedWriter

Intermediate13 min read•Updated: 2026-10-22

Study Materials

📁 File Streams: BufferedReader and BufferedWriter

Introduction

💻 Writing and Reading Files

1import java.io.BufferedWriter;
2import java.io.BufferedReader;
3import java.io.FileWriter;
4import java.io.FileReader;
5import java.io.IOException;
6 
7public class FileIODemo {
8    public static void main(String[] args) {
9        String filename = "students_db.csv";
10 
11        // 1. Fast writing with BufferedWriter
12        try (BufferedWriter writer = new BufferedWriter(new FileWriter(filename))) {
13            writer.write("101,Aarav Sharma,Java Intermediate\n");
14            writer.write("102,Sneha Gupta,Modern C++\n");
15            System.out.println("Records written to " + filename);
16        } catch (IOException e) {
17            e.printStackTrace();
18        }
19 
20        // 2. Fast reading line-by-line with BufferedReader
21        try (BufferedReader reader = new BufferedReader(new FileReader(filename))) {
22            String line;
23            while ((line = reader.readLine()) != null) {
24                System.out.println("Line: " + line);
25            }
26        } catch (IOException e) {
27            e.printStackTrace();
28        }
29    }
30}

Next Lesson

Modern Java NIO: java.nio.file.Path and java.nio.file.Files

Continue learning with hands-on practice, examples, and exercises in the upcoming topic.

Related Lessons

Previous Lesson	Next Lesson
LinkedHashMap and TreeMap for Sorted Key-Value Pairs	Modern Java NIO: java.nio.file.Path and java.nio.file.Files

Practice Quiz

Test your understanding of this lesson with 1 questions. Each question has one correct answer.

Previous Next