Java Input/Output Streams: Fundamentals and Types

Java Input/Output Streams

A concise guide to Java I/O streams, their purpose, and the primary categories.

In Java, streams provide a sequential flow of data between a source and a destination. They abstract the underlying data transport, allowing developers to focus on business logic rather than low‑level I/O handling.

An input stream reads data from a source, while an output stream writes data to a destination.

class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
    }
}

The example above uses System.out—an instance of PrintStream, a concrete output stream—to display text on the console. In contrast, input streams such as System.in enable user input.

We’ll dive deeper into input and output streams in upcoming tutorials.

Types of Streams

Java streams are categorized based on the type of data they handle:

• Byte Streams
• Character Streams

Byte Streams

Byte streams process raw 8‑bit data, making them ideal for binary files such as images, audio, and compressed archives. They inherit from the abstract classes InputStream and OutputStream.

For more details, consult the official documentation:

• Java InputStream Class
• Java OutputStream Class

Character Streams

Character streams handle text data, automatically handling character encoding. They extend the abstract classes Reader and Writer.

For additional information, see:

• Java Reader Class
• Java Writer Class