Java.Streams.Why not use BufferedReader / BufferedWriter always ?

in most real-world scenarios, buffering improves performance and is recommended:

• ✅ Reduces I/O system calls
• ✅ Speeds up character-by-character reading/writing
• ✅ Adds convenient methods: readLine(), newLine()

That’s why BufferedReader and BufferedWriter are used in 90%+ of text-processing code.

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🤔 So… why not always?

There are a few cases where raw (unbuffered) streams/writers might be better:

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1. Very small or one-time I/O

If you’re just writing or reading a few bytes or lines, buffering adds:

• Extra object creation
• Internal memory allocation (buffer arrays)

🔸 Example:

new FileWriter("log.txt").write("Done\n");

In this case, buffering won’t help much and might add unnecessary overhead.

2. Low-latency / Real-time output

Buffered writers only flush data when:

• Buffer is full
• flush() or close() is called

So if you’re writing to a real-time log file, socket, or console, buffering can delay output unless you flush() manually.

🔥 Example:

BufferedWriter writer = new BufferedWriter(new FileWriter("log.txt"));
writer.write("ALERT!");
// The alert won't be in the file until flush/close

This is why logging frameworks usually auto-flush or avoid full buffering.

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3. Memory-sensitive environments

Buffers consume memory (typically 8 KB or more). If you’re dealing with:

• Thousands of parallel I/O streams
• Limited-memory environments (IoT, embedded devices)

You might avoid buffers to reduce memory footprint.

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4. Custom buffering already in place

Sometimes the underlying stream (e.g., a network framework or file cache) already performs buffering. Wrapping it again is unnecessary and may even interfere.

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🧵 TL;DR

Use BufferedReader/Writer when…	Avoid when…
Reading/writing lots of data	Doing minimal I/O
You want performance	You want immediate flush
Working with files/text logs	Memory is tight
Need readLine()	Output needs low latency