%3F instead of question mark in my Retrofit URL

Retrofit won't let you put the query string in the path. Take a look at @QueryMap instead, which is designed for this.

You can achieve it by @QueryName It allows you to attach ? sign at the end of the Url and then the string you want after "?" Sign You may also need to look at @QueryName(encoded = true) if your string is already encoded.

As refs: https://square.github.io/retrofit/2.x/retrofit/index.html?retrofit2/http/QueryMap.html

I use @QueryMap and ImmutableMap.

In my case, the API is: /api/static_pages/?q=A+B+C

My solution:

Step 1:

@GET("/api/static_pages")
    Call<String> getStaticPagesByType(@HeaderMap HashMap<String, Object> header,
                               @QueryMap(encoded=true) Map<String, String> filters);

Step 2: When I want to call API:

List<String> listTypes = new ArrayList<>();
listTypes.add("A");
listTypes.add("B");
listTypes.add("C");

StringBuilder typeString = new StringBuilder();

int listSize = listType.size();

for (int i = 0; i < listSize - 1; i++) {
    typeString.append(listType.get(i));
    if(i != listSize-2){
       typeString.append("+");
    }
}
// The key is here!
ImmutableMap<String, String> types = ImmutableMap.of("q", typeString.toString());
getRetrofitClient().getStaticPagesByType(yourHeader, types)

Hope it help your work.

Happy coding.