Add an array as request parameter with Retrofit 2

I have finally founded a solution by using Arrays.toString(int []) method and by removing spaces in this result because Arrays.toString return "[0, 1, 3, 5]". And my request method looks like this

@GET("http://server/service")
Observable<Void> getSomething(@Query("array") String array);

I faced a similar problem and had to do a couple of things to reach the acceptable form (as asked in the question).

1. Converted an ArrayList to String

   arrayList.toString().replace(" ", "")
   

2. In RetroFit method, I changed the Query param which accepts the ArrayList above to as follows:

   @Query(value = "cities", encoded = true)
   

This ensures that the brackets and commas are not URL encoded.

Just add it as a query param

@GET("http://server/service")
Observable<Void> getSomething(@Query("array") List<Integer> array);

You can also use int[], or Integer... as a last param;

You need to name your query param with an array syntax like so:

@GET("http://server/service")
Observable<Void> getSomething(@Query("array[]") List<Integer> array);

The syntax itself will vary by the backend technology being used, however not including the brackets "[]" will normally be interpreted as a single value.

For example, using array=1&array=2 will generally be interpreted by backends as only array=1 or array=2 instead of array=[1,2].