openConnection

openConnection is a method in the Java programming language found in the java.net.URL class. It creates a URLConnection object that represents a communication link to the resource identified by the URL. The method returns a URLConnection, whose actual runtime type depends on the protocol and implementing library (for example, an HttpURLConnection for HTTP/HTTPS URLs).

There are two overloads: openConnection() and openConnection(Proxy proxy). The version with a Proxy allows you to specify a network proxy for the connection. The connection is not necessarily established when the method is called; in many cases, the connection is opened when data is read or when an explicit connect() call is made.

Typical usage involves creating a URL, obtaining a URLConnection, configuring the connection, and then accessing data. A common sequence is to call openConnection to obtain the connection, set request properties or timeouts via the URLConnection (or its subclass, such as HttpURLConnection), and then call connect or access the input/output streams to transfer data. The getInputStream() and getOutputStream() methods trigger the actual I/O, with some implementations performing the connection lazily on first use. In HTTP-based connections, the concrete class is often HttpURLConnection, which provides additional methods for request methods, status codes, and headers.

openConnection is part of the standard Java API for network communication and is a foundational step in interacting with remote resources through URL-based protocols. See also HttpURLConnection, URLConnection, and java.net.Proxy.