MalformedURLException although I have already replaced spaces with %20

Question

String url = "http://maps.googleapis.com/maps/api/distancematrix/xml?origins="+origin+"&destinations="+destination+"&mode=driving&sensor=false&language=en-EN&units=imperial";
url = url.replaceAll(" ", "%20");

Output :

http://maps.googleapis.com/maps/api/distancematrix/xml?origins=150%20Sutter%20St%20San%20Francisco,%20CA,%20United%20States&destinations=1%20Palmer%20Sq%20E
Princeton,%20NJ%2008542&mode=driving&sensor=false&language=en-EN&units=imperial

But I am getting an error saying :

java.net.MalformedURLException: Illegal character in URL

Can some one help me out ..

Answer 1

(Note: see update below)

Use the URLEncoder class from the java.net package. Spaces are not the only characters that need to be escaped in URLs, and the URLEncoder will make sure that all characters that need to be encoded are properly encoded.

Here's a small example:

String url = "http://...";
String encodedUrl = null;

try {
    encodedUrl = URLEncoder.encode(url, "UTF-8");
} catch (UnsupportedEncodingException ignored) {
    // Can be safely ignored because UTF-8 is always supported
}

Update

As pointed out in the comments and other answers to this question, the URLEncoder class is only safe to encode the query string parameters of a URL. I currently rely on Guava's UrlEscapers to safely encode different parts of a URL.