I/O Streams & Buffers 🚀

Mentor's Note: Reading data from a disk is one of the slowest things a computer does. Buffering is how we "Hack" this speed limit to make our programs lightning-fast! 💡

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🌟 The Scenario: The Hose vs. The Bucket 🪣

Imagine you are filling a swimming pool from a well.

• The Stream (The Hose): You carry one small cup of water at a time from the well to the pool. (Character-by-character). 📦
• The Buffer (The Big Bucket): You use a giant bucket. You fill it at the well, carry the whole bucket, and pour it into the pool in one go. 📦
• The Result: You finish the job much faster because you make fewer trips. This is exactly what a BufferedReader does for your data! ✅

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📖 The Hierarchy of Streams

1. Byte Streams (8-bit) 🔢

Used for handling raw binary data like images or audio. - Classes: FileInputStream, FileOutputStream.

2. Character Streams (16-bit) 🔡

Used for handling text data (Unicode). - Classes: FileReader, FileWriter.

3. Buffered Streams (The Accelerators) 🏎️

They add a "Bucket" (Memory area) to existing streams to reduce disk access. - Classes: BufferedReader, BufferedWriter.

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🎨 Visual Logic: The Buffered Path

graph LR
    A[Hard Drive 💿] -- "Small Drops" --> B["InputStream (Slow) ⏳"]
    A -- "Bulk Load" --> C["Buffer (Memory) 🪣"]
    C -- "Instant Access" --> D["Your Program 🐍"]

    style C fill:#dfd,stroke:#333

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💻 Implementation: The Performance Lab

The Professional Way (Buffered)

import java.io.*;

public class Main {
    public static void main(String[] args) {
        // 🛒 Scenario: Reading a long text file
        // 🚀 Action: Wrapping FileReader inside a BufferedReader

        try (BufferedReader reader = new BufferedReader(new FileReader("data.txt"))) {
            String line;
            while ((line = reader.readLine()) != null) {
                System.out.println("Processing: " + line);
            }
        } catch (IOException e) {
            System.out.println("Error: " + e.getMessage());
        }
    }
}

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📊 Sample Dry Run (BufferedReader)

Task: Read 1KB file

Component	Logic	Result
FileReader	Ask Disk for 1 character	SLOW (Wait for hardware) ⏳
BufferedReader	Ask Disk for 8KB chunk	FAST (One big pull) 🏎️
Next Line	Read from Memory	INSTANT ⚡

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📈 Technical Analysis

• Standard Buffer Size: Default is 8192 characters (8KB).
• Line Endings: readLine() automatically handles \n or \r\n regardless of the Operating System. 🌐

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🎯 Practice Lab 🧪

Task: The Data Copier

Task: Write a program that reads input.txt and copies its content into a new file output.txt using Buffered Streams. Hint: Use reader.readLine() and writer.write(). 💡

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💡 Interview Tip 👔

"Interviewers love asking: 'When should you use FileInputStream vs FileReader?' Answer: Use Stream for Binary files (Images/PDFs) and Reader for Text files (Notepad/Logs)!"

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💡 Pro Tip: "One interface, multiple implementations—that's the power of being flexible!" - Anonymous

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