Graph API wants photo URL while I have an URI

Question

I was trying to use Graph API Post to post an image to FaceBook, I tested it on the Graph Api Explorer with :
link (if you'll test it then replace Page_ID with your page id): Page_ID/photos
JSON :

{
  "message": "hello japan",
  "transport": "cors",
  "url": "https://helpx.adobe.com/content/dam/help/en/photoshop/using/convert-color-image-black-white/jcr_content/main-pars/before_and_after/image-before/Landscape-Color.jpg"
}

and worked as expected.

but now I want to post using my android app using my external/internal storage photos where I only have their Uri while it needs a URL to the image telling me every time

{HttpStatus: 400, errorCode: 1, subErrorCode: -1, errorType: OAuthException, errorMessage: (#1) Could not fetch picture}

so how should I get a URL that represent my Uri that looks like this :

content://media/external/images/media/26281

my code :

private int postRandomData(String photo_uri,String msg, List<PageEntity> pageEntities) {
        ArrayList<GraphRequest> requests = new ArrayList<>();
        Bundle parameters = new Bundle();
        parameters.putString("message",msg);
        parameters.putString("url", photo_uri);
        GraphRequest.Callback callback = response -> {
            if (response.getError() == null) {
                //TODO handle error codes
                Log.e("response", response.toString());
            }
        };
        for (PageEntity pageEntity : pageEntities) {
            AccessToken pageAccessToken = createAccessToken(pageEntity.getPageAccessToken(), pageEntity.getPageId());
            requests.add(createPostRequest(callback, pageAccessToken, parameters));
            }
          GraphRequest.executeBatchAsync(requests)
}
public GraphRequest createPostRequest(GraphRequest.Callback callback, AccessToken accessToken, Bundle parameters) {
        GraphRequest request = null;
        try {
            request = GraphRequest.newPostRequest(accessToken, "/" + accessToken.getUserId() + "/picture", new JSONObject("{}"), callback);
            request.setParameters(parameters);
        } catch (JSONException exception) {
            exception.printStackTrace();
        }
        return request;
}
public AccessToken createAccessToken(String accessTokenString, String id) {
        AccessToken currentAccessToken = AccessToken.getCurrentAccessToken();
        return new AccessToken(accessTokenString
                , currentAccessToken.getApplicationId()
                , id
                , currentAccessToken.getPermissions()
                , currentAccessToken.getDeclinedPermissions()
                , currentAccessToken.getExpiredPermissions()
                , currentAccessToken.getSource()
                , currentAccessToken.getExpires()
                , currentAccessToken.getLastRefresh()
                , currentAccessToken.getDataAccessExpirationTime());
}