How to show if a String is a URL Android

This example uses a relatively simple regular expression for URL validation. For more robust validation, you might consider a more comprehensive regex or a dedicated library. It's important to note that this function only checks for basic URL syntax. It doesn't verify that the URL actually exists or is accessible.

A simple Kotlin example to show if a string is a URL.

import java.util.regex.Pattern

fun isUrl(urlString: String): Boolean {
  val urlPattern = Pattern.compile(
      "^((https?|ftp|gopher|telnet|file|news|data)://)" +
  return urlPattern.matcher(urlString).matches()

fun main() {
  val validUrl = ""
  val invalidUrl = "This is not a URL"

  println("Is '$validUrl' a URL? ${isUrl(validUrl)}") // Output: true
  println("Is '$invalidUrl' a URL? ${isUrl(invalidUrl)}") // Output: false

Import java.util.regex.Pattern: This imports the necessary class for working with regular expressions.

isUrl(urlString: String): Boolean Function:

  • Takes a String representing the potential URL.
  • Creates a Pattern object using a regular expression to match URLs. This regex checks for common URL patterns, including protocol, domain, and path.
  • Uses matcher() to create a Matcher object for the input string.
  • Calls matches() to check if the input string matches the regular expression.
  • Returns true if the string is a valid URL, false otherwise.

main() Function:

  • Defines two strings, one a valid URL and the other not.
  • Calls isUrl() for each string and prints the results.