Java.Streams.

🔄 Commonalities

Feature	InputStream / OutputStream	Reader / Writer
Belong to	java.io package	java.io package
Abstract classes	Yes ✅	Yes ✅
Base for stream hierarchy	Yes ✅	Yes ✅
Support chaining/wrapping	Yes ✅	Yes ✅ (e.g., with buffering)
Need to be closed	Yes ✅ (implements Closeable)	Yes ✅ (implements Closeable)
Support try-with-resources	Yes ✅	Yes ✅

So all four are abstract base classes that handle I/O streams, support stream composition (via decorators like Buffered*), and must be explicitly closed (or auto-closed with try-with-resources).

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📊 Key Differences

Feature	InputStream	OutputStream	Reader	Writer
📦 Type	Byte-based	Byte-based	Character-based	Character-based
🔁 Direction	Read	Write	Read	Write
🔢 Operates on	byte (8-bit)	byte (8-bit)	char (16-bit Unicode)	char (16-bit Unicode)
🧠 Use Case	Read binary data (e.g. files, images)	Write binary data	Read text (files, strings)	Write text
🎯 Example Classes	FileInputStream, BufferedInputStream	FileOutputStream, PrintStream	BufferedReader, FileReader	BufferedWriter, PrintWriter

🎨 Visual Summary

Byte Streams (Raw Data)
 ┌──────────────┐           ┌──────────────┐
 │ InputStream  │◄────Read──┤ Binary Source│
 └──────────────┘           └──────────────┘
 ┌──────────────┐           ┌──────────────┐
 │OutputStream  │───Write──►│ Binary Sink  │
 └──────────────┘           └──────────────┘

Character Streams (Text Data)
 ┌────────┐           ┌──────────────┐
 │ Reader │◄────Read──┤ Text Source  │
 └────────┘           └──────────────┘
 ┌────────┐           ┌──────────────┐
 │ Writer │───Write──►│ Text Sink    │
 └────────┘           └──────────────┘

🧪 Example Use Cases

Task	Best Option
Read a binary file (e.g. image)	InputStream
Write raw bytes to a socket	OutputStream
Read lines from a text file	BufferedReader
Write formatted text to a file	PrintWriter

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🧵 TL;DR

Category	Byte Streams	Character Streams
Base Classes	InputStream / OutputStream	Reader / Writer
Use When	Working with binary data	Working with text
Examples	Image files, network sockets	Text files, logs, console