Android java 通过特殊字符拆分字符串失败

Question

I would like to attach a platform parameter to a url with ? if the url has no query string and using & if url has a query string

SO i have added the following

 String api_url;
 //costructor next to assign apiurl value

 //method to extract url and process request
 processData(){
    String apiUrl = "";
    String[] urlParams = this.api_url.split("\\?");
    if (urlParams.length > 0){
        apiUrl = this.api_url+"&platform="+tokenService.getToken(AppDetailsHelpers.AppSettingsKeys.PLATFORM);
    }else {
        apiUrl = this.api_url+"?platform="+tokenService.getToken(AppDetailsHelpers.AppSettingsKeys.PLATFORM);
    }
}

The above always evaluates the urlParams to a an array even when a url doesnt contain the ?

Example for a url

http://test.com

is resolved with the above code as

http://test.com&platform=12

But i expected it to be as http://test.com?platform=12

I have tried adding

String[] urlParams = this.api_url.split("?"); 

But it throws an error of Dangling metacharacter . What am i missing out on this. Why does this fail.

Answer 1

This is expected behaviour for String#split . Running "http://test.com".split("\\?") returns an array with one element, "http://test.com" . So, just update your condition to if(uriParams.length > 1) .

You could also consider parsing your String to a Uri, as you may not need this check and could possibly instead use:

Uri.parse(api_url)
    .buildUpon()
    .appendQuery("platform", tokenService.getToken(AppSettingsKeys.PLATFORM))
    .build().toString();