URLException

A URLException is a type of exception in Java that is thrown when an error related to a Uniform Resource Identifier (URI) or Uniform Resource Locator (URL) occurs. These exceptions are part of the java.net package and indicate problems that prevent a program from accessing or processing a web resource.

There are two main subclasses of URLException: MalformedURLException and UnknownHostException. A MalformedURLException is typically thrown when the syntax of the URL string is incorrect, meaning it doesn't conform to the expected format for a valid URL. This could be due to missing components like the protocol (e.g., "http"), an invalid character, or an improperly structured path.

An UnknownHostException, on the other hand, is a subclass of IOException, but it's often encountered in conjunction with URL operations. It signifies that the host name specified in the URL could not be resolved to an IP address. This usually happens when there is a network connectivity issue, the DNS server is unavailable, or the hostname itself is incorrect or does not exist.

When a URLException is thrown, it means that the Java runtime environment encountered an unrecoverable error while attempting to interpret or connect to the specified resource. Programmers typically handle these exceptions using try-catch blocks to gracefully manage situations where a URL is invalid or inaccessible, preventing the application from crashing and allowing for alternative actions or user feedback.