Android: how to parse URL String with spaces to URI object?

You should in fact URI-encode the "invalid" characters. Since the string actually contains the complete URL, it's hard to properly URI-encode it. You don't know which slashes / should be taken into account and which not. You cannot predict that on a raw String beforehand. The problem really needs to be solved at a higher level. Where does that String come from? Is it hardcoded? Then just change it yourself accordingly. Does it come in as user input? Validate it and show error, let the user solve itself.

At any way, if you can ensure that it are only the spaces in URLs which makes it invalid, then you can also just do a string-by-string replace with %20:

URI uri = new URI(string.replace(" ", "%20"));

Or if you can ensure that it's only the part after the last slash which needs to be URI-encoded, then you can also just do so with help of android.net.Uri utility class:

int pos = string.lastIndexOf('/') + 1;
URI uri = new URI(string.substring(0, pos) + Uri.encode(string.substring(pos)));

Do note that URLEncoder is insuitable for the task as it's designed to encode query string parameter names/values as per application/x-www-form-urlencoded rules (as used in HTML forms). See also Java URL encoding of query string parameters.

To handle spaces, @, and other unsafe characters in arbitrary locations in the url path, Use Uri.Builder in combination with a local instance of URL as I have described here:

private Uri.Builder builder;
public Uri getUriFromUrl(String thisUrl) {
    URL url = new URL(thisUrl);
    builder =  new Uri.Builder()
                            .scheme(url.getProtocol())
                            .authority(url.getAuthority())
                            .appendPath(url.getPath());
    return builder.build();
}

java.net.URLEncoder.encode(finalPartOfString, "utf-8");

This will URL-encode the string.

finalPartOfString is the part after the last slash - in your case, the name of the song, as it seems.

URL url = Test.class.getResource(args[0]);  // reading demo file path from                                                   
                                            // same location where class                                    
File input=null;
try {
    input = new File(url.toURI());
} catch (URISyntaxException e1) {
    // TODO Auto-generated catch block
    e1.printStackTrace();
}