java.net

About

The java.net package provides classes for implementing networking applications in Java. It offers support for both low-level communication (e.g., sockets) and high-level abstractions (e.g., URLs). This package is essential for creating Java applications that communicate over TCP/IP, including web clients, servers, and distributed systems.

It allows developers to work with IP addresses, hostnames, ports, sockets, datagrams, and HTTP requests.

Key Classes and Interfaces

URL

Represents a Uniform Resource Locator, a pointer to a "resource" on the World Wide Web. Useful methods: openConnection(), getHost(), getPath(), getProtocol().

URLConnection

Represents a communication link between the application and a URL. Allows you to read from and write to a resource referenced by a URL.

InetAddress

Represents an IP address. Used for DNS resolution and IP-level information. Key methods: getByName(), getLocalHost(), getHostAddress().

Socket

Implements client-side TCP connections. Allows bi-directional communication with a server. Used with InputStream and OutputStream.

ServerSocket

Implements server-side TCP communication. Listens on a port and accepts incoming connections. Used to create socket-based servers.

DatagramSocket

Implements UDP communication. Sends and receives datagram packets (connectionless). Used when low-latency and stateless communication is required.

DatagramPacket

Represents a data packet sent or received via DatagramSocket.

URI

Represents a Uniform Resource Identifier and provides methods for parsing and validating URIs.

HttpURLConnection

A subclass of URLConnection that supports HTTP-specific features such as request methods, headers, response codes.