How can I return a href within a string, I can access the start position but not sure how to get last position :

Here is what I have so far :

    String str = "sadf ad fas dfa http:\\www.google.com sdfa sadf as dfas";

    int index = str.indexOf("http");
    String href = str.substring(index , ???);

What should the end index be ?

Note, this is targeted at j2me & I need to minimise download footprint so I cannot use regular expressions or third party regular expressions libraries.