Byte streams (InputStream/OutputStream and subclasses) handle raw binary data one byte at a time — used for images, audio, any non-text data. Character streams (Reader/Writer and subclasses) handle text, automatically converting between bytes and characters using a specified (or platform default) charset encoding.

Intermediate5 min

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#Byte Streams#Character Streams

What is the difference between byte streams and character streams in Java?

Why Charset Awareness Matters

Using a byte stream on text data (or vice versa) is a common source of subtle bugs — a character stream correctly decodes multi-byte UTF-8 sequences into the right characters, while treating that same text as raw bytes can corrupt non-ASCII characters if the byte boundaries don't align with character boundaries.

Byte streams: raw bytes, binary data · Character streams: charset-aware, text data

Byte vs Character Stream

java

// Byte stream — raw bytes, e.g. for images
try (FileInputStream fis = new FileInputStream("image.png")) { ... }

// Character stream — text, charset-aware
try (FileReader fr = new FileReader("notes.txt")) { ... }