java.net.URL Class in Java

URL is an acronym of Uniform resource locator. It is a pointer to locate resource in www (World Wide Web). A resource can be anything from a simple text file to any other like images, file directory etc. 

The typical URL may look like

http://www.example.com:80/index.html

The URL has the following parts:

• Protocol: In this case the protocol is HTTP, It can be HTTPS in some cases
• Hostname: Hostname represent the address of the machine on which resource is located, in this case, www.example.com
• Port Number: It is an optional attribute. If not specified then it returns -1. In the above case, the port number is 80.
• Resource name: It is the name of a resource located on the given server that we want to see

You can learn more about the URL here.

The Class structure of the URL is as shown below:

public final class java.net.URL extends java.lang.Object

The Following are constructors provided by the URL class.

Constructor	Explanation
public URL(String  url )	This constructor creates an object of URL class from given string representation
public URL(String  protocol, String  host, int  port, String  file)	This constructor creates an object of URL from the specified protocol, host, port number, and file.
public URL(String  protocol, String  host, String  file)	This constructor creates an object of URL from the specified protocol, port number, and file. The default port number is used in this case.
public URL(URL  context, String  src)	This constructor creates an instance of a URL by parsing the given src with the specified handler within a given context.

Methods Provided by URL Class:

Method	Explanation
equals(Object obj)	This method compares this URL for equality with another object.
getAuthority()	This method gets the authority part of this URL.
getContent()	This method gets the contents of this URL.
getContent(Class[] classes)	This method gets the contents of this URL.
getDefaultPort()	This method gets the default port number of the protocol associated with this URL.
getFile()	This method gets the file name of this URL.
getHost()	This method gets the hostname of this URL, if applicable.
getPath()	This method gets the path part of this URL.
getPort()	This method gets the port number of this URL.
getProtocol()	This method gets the protocol name of this URL.
getQuery()	This method gets the query part of this URL.
getRef()	This method gets the anchor (also known as the “reference”) of this URL.
getUserInfo()	This method gets the userInfo part of this URL.
hashCode()	This method creates an integer suitable for hash table indexing.
openConnection()	This method returns a URLConnection instance that represents a connection to the remote object referred to by the URL.
openConnection(Proxy proxy)	Same as openConnection(), except that the connection will be made through the specified proxy; Protocol handlers that do not support proxing will ignore the proxy parameter and make a normal connection.
openStream()	This method opens a connection to this URL and returns an InputStream for reading from that connection.
sameFile(URL other)	This method compares two URLs, excluding the fragment component.
set(String protocol, String host, int port, String file, String ref)	This method sets the fields of the URL.
set(String protocol, String host, int port, String authority, String userInfo, String path, String query, String ref)	This method sets the specified 8 fields of the URL.
setURLStreamHandlerFactory(URLStreamHandlerFactory fac)	This method sets an application’s URLStreamHandlerFactory.
toExternalForm()	This method constructs a string representation of this URL.
toString()	This method constructs a string representation of this URL.
toURI()	This method returns a URI equivalent to this URL.

Demonstration 1

In this demonstration, we are going to create an object of URL class for a given String URL, and we are going to print hostname, protocol, filename and Port number for given URL.

Java

// importing package required
import java.net.URL;
import java.util.Scanner;

class GFG {
    public static void main(String[] args)
    {
        String url
            = "https://www.geeksforgeeks.org/variables-in-java/";
        // Calling method to get URL info
        getUrlInfo(url);
    }
    static void getUrlInfo(String url_string)
    {
        // Creating object of URL class
        try {
            URL url = new URL(url_string);

            System.out.println("Hostname: "
                               + url.getHost());
            System.out.println("Port Number: "
                               + url.getPort());
            System.out.println("File name: "
                               + url.getFile());
            System.out.println("Protocol:  "
                               + url.getProtocol());
        }
        catch (Exception e) {
        }
    }
}

Output

Hostname: www.geeksforgeeks.org
Port Number: -1
File name: /variables-in-java/
Protocol:  https