Android: fill a spinner data from the server dynamically

Question

I'm new to android. How do you fill a spinner from the server's data dynamically.

So I'm trying to populate data from the server to my spinner. my JSON is

{"topic": "/waypoints", "msg": {"waypoints": [{"header": {"stamp": {"secs": 0, "nsecs": 0}, "frame_id": "map", "seq": 0}, "pose": {"position": {"y": -140.901899144836, "x": 44.36469369653882, "z": 0.0}, "orientation": {"y": 0.0, "x": 0.0, "z": 0.5062775131960053, "w": 0.8623706161692133}}, "name": "A"}, {"header": {"stamp": {"secs": 0, "nsecs": 0}, "frame_id": "map", "seq": 0}, "pose": {"position": {"y": -102.30524463734227, "x": 51.282396271771304, "z": 0.0}, "orientation": {"y": 0.0, "x": 0.0, "z": 0.6926372547579506, "w": 0.721286096719859}}, "name": "B"}]}, "op": "publish"}

Now I'm trying to get only "name": A and B, and when i select each of them there will be the information of the orientation and the position. Thanks in Advance!

EDIT

so basically this is a pop up window of my waypoints. and I'm struggling to fix "(String json)" for my method part.

public class Pop extends Activity {

private SubscribedData<WaypointList> waypointlistData;
private RosbridgeListener rosbridge;
Spinner spin;
String json;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.popup);

    /** an ID for the spinner **/
    spin = (Spinner) findViewById(R.id.spinner);

    /** publisher definition with its type of message**/
    waypointlistData = new SubscribedData<>();
    final Type waypointlistType = new TypeToken<SubscribedData<WaypointList>>() {
    }.getType();


    /** A method to parse a jsonstring to waypoint list **/
    private List<Waypoint> getWayPointListFromJsonString(String json){
        List<Waypoint> wayPoints = new ArrayList<>();
        try {
            JSONObject jsonObject = new JSONObject(json);
            JSONArray wayPointJsonArray = jsonObject.getJSONObject("msg").getJSONArray("waypoints");
            for (int i = 0; i < wayPointJsonArray.length(); i++) {
                JSONObject wayPointJsonObject = wayPointJsonArray.getJSONObject(i);
                // Parse name
                String name = wayPointJsonObject.getString("name");

                // Parse pose to get position and orientation;
                JSONObject poseJsonObject = wayPointJsonObject.getJSONObject("pose");

                // Parse position form pose
                JSONObject positionJsonObject = poseJsonObject.getJSONObject("position");
                Position position = new Position();
                position.x = positionJsonObject.getFloat("x");
                position.y = positionJsonObject.getFloat("y");
                position.z = positionJsonObject.getFloat("z");

                // Parse orientation from pose.
                JSONObject orientationJsonObject = poseJsonObject.getJSONObject("orientation");
                Orientation orientation = new Orientation();
                orientation.x = orientationJsonObject.getFloat("x");
                orientation.y = orientationJsonObject.getFloat("y");
                orientation.z = orientationJsonObject.getFloat("z");
                orientation.w = orientationJsonObject.getFloat("w");

                Pose pose = new Pose();
                pose.position = position;
                pose.orientation = orientation;

                Waypoint wayPoint = new Waypoint();
                wayPoint.name = name;
                wayPoint.pose = pose;
                wayPoints.add(wayPoint);
            }
        } catch (JSONException e) {
            e.printStackTrace();
        }
        return wayPoints;
    }

    // This is the json string returned from server.
    String jsonString = "{\"topic\": \"/waypoints\", \"msg\": {\"waypoints\": [{\"header\": {\"stamp\": {\"secs\": 0, \"nsecs\": 0}, \"frame_id\": \"map\", \"seq\": 0}, \"pose\": {\"position\": {\"y\": -140.901899144836, \"x\": 44.36469369653882, \"z\": 0.0}, \"orientation\": {\"y\": 0.0, \"x\": 0.0, \"z\": 0.5062775131960053, \"w\": 0.8623706161692133}}, \"name\": \"A\"}, {\"header\": {\"stamp\": {\"secs\": 0, \"nsecs\": 0}, \"frame_id\": \"map\", \"seq\": 0}, \"pose\": {\"position\": {\"y\": -102.30524463734227, \"x\": 51.282396271771304, \"z\": 0.0}, \"orientation\": {\"y\": 0.0, \"x\": 0.0, \"z\": 0.6926372547579506, \"w\": 0.721286096719859}}, \"name\": \"B\"}]}, \"op\": \"publish\"}";

    // This will convert the json string to list of WayPoint
    List<Waypoint> wayPoints = getWayPointListFromJsonString(jsonString);

    // Create adapter for spinner
    SpinnerAdapter adapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, wayPoints);

    spin.setAdapter(adapter);
    spin.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {

        @Override
        public void onItemSelected(AdapterView<?> parent, View view, int p, long id) {
            Waypoint wayPoint = (Waypoint) parent.getItemAtPosition(p);

            // Process position here
            Position position = wayPoint.pose.position;

            // Process orientation here
            Orientation orientation = wayPoint.pose.orientation;
        }

        @Override
        public void onNothingSelected(AdapterView<?> parent) {
        }
    });

        /** a set of the waypoints popup window **/
    DisplayMetrics dm = new DisplayMetrics();
    getWindowManager().getDefaultDisplay().getMetrics(dm);

        int width = dm.widthPixels;
        int height = dm.heightPixels;

        getWindow().setLayout((int) (width * .6), (int) (height * .6));


}

}

Answer 1

you first need to deserialize the data and map to model class and then set the model list to spinner adapter. Check retrofit to request and parse your Jason response.

Answer 2

 for (int i = 0; i < arrResult.length(); i++) {
     arr_akun[i] = "string dynamically";
 }

 ArrayAdapter<String> adapter_akun = new ArrayAdapter<>(context, R.layout.spinner_akun_item, arr_akun);
 spinner.setAdapter(adapter_akun);

 spinner_akun.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
     // do something to get name
        }

        @Override
        public void onNothingSelected(AdapterView<?> parent) {
        }
    });

Answer 3

Each item in spinner indicates one "WayPoint". So first step is create model class for WayPoint.

class WayPoint {
    String name;
    Pose pose;

    @NonNull
    @Override
    public String toString() {
        return name;
    }
}

class Pose {
    Position position;
    Orientation orientation;
}

class Position {
    double x, y, z;
}

class Orientation {
    double x, y, z, w;
}

Second, write a method to parse a json string to way point list

private List<WayPoint> getWayPointListFromJsonString(String json) {
    List<WayPoint> wayPoints = new ArrayList<>();

    try {
        JSONObject jsonObject = new JSONObject(json);
        JSONArray wayPointJsonArray = jsonObject.getJSONObject("msg").getJSONArray("waypoints");
        for (int i = 0; i < wayPointJsonArray.length(); i++) {
            JSONObject wayPointJsonObject = wayPointJsonArray.getJSONObject(i);

            // Parse name
            String name = wayPointJsonObject.getString("name");

            // Parse pose to get position and orientation;
            JSONObject poseJsonObject = wayPointJsonObject.getJSONObject("pose");

            // Parse position form pose
            JSONObject positionJsonObject = poseJsonObject.getJSONObject("position");
            Position position = new Position();
            position.x = positionJsonObject.getDouble("x");
            position.y = positionJsonObject.getDouble("y");
            position.z = positionJsonObject.getDouble("z");

            // Parse orientation from pose.
            JSONObject orientationJsonObject = poseJsonObject.getJSONObject("orientation");
            Orientation orientation = new Orientation();
            orientation.x = orientationJsonObject.getDouble("x");
            orientation.y = orientationJsonObject.getDouble("y");
            orientation.z = orientationJsonObject.getDouble("z");
            orientation.w = orientationJsonObject.getDouble("w");

            Pose pose = new Pose();
            pose.position = position;
            pose.orientation = orientation;

            WayPoint wayPoint = new WayPoint();
            wayPoint.name = name;
            wayPoint.pose = pose;
            wayPoints.add(wayPoint);
        }
    } catch (JSONException e) {
        e.printStackTrace();
    }

    return wayPoints;
}

Finally put them into MainActivity class.

public class MainActivity extends AppCompatActivity {

    private Spinner wayPointSpinner;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        wayPointSpinner = findViewById(R.id.spinner_way_point);

        // This is the json string returned from server.
        String jsonString = "{\"topic\": \"/waypoints\", \"msg\": {\"waypoints\": [{\"header\": {\"stamp\": {\"secs\": 0, \"nsecs\": 0}, \"frame_id\": \"map\", \"seq\": 0}, \"pose\": {\"position\": {\"y\": -140.901899144836, \"x\": 44.36469369653882, \"z\": 0.0}, \"orientation\": {\"y\": 0.0, \"x\": 0.0, \"z\": 0.5062775131960053, \"w\": 0.8623706161692133}}, \"name\": \"A\"}, {\"header\": {\"stamp\": {\"secs\": 0, \"nsecs\": 0}, \"frame_id\": \"map\", \"seq\": 0}, \"pose\": {\"position\": {\"y\": -102.30524463734227, \"x\": 51.282396271771304, \"z\": 0.0}, \"orientation\": {\"y\": 0.0, \"x\": 0.0, \"z\": 0.6926372547579506, \"w\": 0.721286096719859}}, \"name\": \"B\"}]}, \"op\": \"publish\"}";

        // This will convert the json string to list of WayPoint
        List<WayPoint> wayPoints = getWayPointListFromJsonString(jsonString);

        // Create adapter for spinner
        SpinnerAdapter adapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, wayPoints);

        wayPointSpinner.setAdapter(adapter);
        wayPointSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {

            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int p, long id) {
                WayPoint wayPoint = (WayPoint) parent.getItemAtPosition(p);

                // Process position here
                Position position = wayPoint.pose.position;

                // Process orientation here
                Orientation orientation = wayPoint.pose.orientation;
            }

            @Override
            public void onNothingSelected(AdapterView<?> parent) {
            }
        });
    }
}