Regex to check with starts with http://, https:// or ftp://

Question

I am framing a regex to check if a word starts with http:// or https:// or ftp://, my code is as follows,

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Answer 1

test.matches() method checks all text.use test.find()

Answer 2

You need a whole input match here.

System.out.println(test.matches("^(http|https|ftp)://.*$")); 

Edit:(Based on @davidchambers's comment)

System.out.println(test.matches("^(https?|ftp)://.*$")); 

Answer 3

If you wanna do it in case-insensitive way, this is better:

System.out.println(test.matches("^(?i)(https?|ftp)://.*$")); 

Answer 4

Unless there is some compelling reason to use a regex, I would just use String.startsWith:

bool matches = test.startsWith("http://")
            || test.startsWith("https://") 
            || test.startsWith("ftp://");

I wouldn't be surprised if this is faster, too.

Answer 5

I think the regex / string parsing solutions are great, but for this particular context, it seems like it would make sense just to use java's url parser:

https://docs.oracle.com/javase/tutorial/networking/urls/urlInfo.html

Taken from that page:

import java.net.*;
import java.io.*;

public class ParseURL {
    public static void main(String[] args) throws Exception {

        URL aURL = new URL("http://example.com:80/docs/books/tutorial"
                           + "/index.html?name=networking#DOWNLOADING");

        System.out.println("protocol = " + aURL.getProtocol());
        System.out.println("authority = " + aURL.getAuthority());
        System.out.println("host = " + aURL.getHost());
        System.out.println("port = " + aURL.getPort());
        System.out.println("path = " + aURL.getPath());
        System.out.println("query = " + aURL.getQuery());
        System.out.println("filename = " + aURL.getFile());
        System.out.println("ref = " + aURL.getRef());
    }
}

yields the following:

protocol = http
authority = example.com:80
host = example.com
port = 80
path = /docs/books/tutorial/index.html
query = name=networking
filename = /docs/books/tutorial/index.html?name=networking
ref = DOWNLOADING