Try using this
public interface SafeUserApi {
@FormUrlEncoded
@POST("/api/userlogin")
void getUserLogin(
@Field("client_id") String id,
@Field("client_secret") String secret,
@Field("username") String uname,
@Field("password") String password,
Callback<LoginResult> cb
);
}
Here parm1 is the POST parameter that you will be passing it to the server.
This will solve your problem
in case if you are using PHP u can access the param1 using $uname= $_POST('username');
EDIT 1:
retrofit 2.0 version:
public interface SafeUserApi {
@FormUrlEncoded
@POST("/api/userlogin")
Call<ResponseBody> getUserLogin(
@Field("client_id") String id,
@Field("client_secret") String secret,
@Field("username") String uname,
@Field("password") String password
);
}