platform/android/MapboxGLAndroidSDKTestApp/src/main/java/com/mapbox/mapboxsdk/testapp/utils/GeoParseUtil.java


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package com.mapbox.mapboxsdk.testapp.utils;

import android.content.Context;
import android.text.TextUtils;

import com.mapbox.mapboxsdk.geometry.LatLng;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.List;

public class GeoParseUtil {

  public static String loadStringFromAssets(final Context context, final String fileName) throws IOException {
    if (TextUtils.isEmpty(fileName)) {
      throw new NullPointerException("No GeoJSON File Name passed in.");
    }
    InputStream is = context.getAssets().open(fileName);
    BufferedReader rd = new BufferedReader(new InputStreamReader(is, Charset.forName("UTF-8")));
    return readAll(rd);
  }

  public static List<LatLng> parseGeoJsonCoordinates(String geojsonStr) throws JSONException {
    List<LatLng> latLngs = new ArrayList<>();
    JSONObject jsonObject = new JSONObject(geojsonStr);
    JSONArray features = jsonObject.getJSONArray("features");
    int featureLength = features.length();
    for (int j = 0; j < featureLength; ++j) {
      JSONObject feature = features.getJSONObject(j);
      JSONObject geometry = feature.getJSONObject("geometry");
      String type = geometry.getString("type");
      JSONArray coordinates;
      if (type.equals("Polygon")) {
        coordinates = geometry.getJSONArray("coordinates").getJSONArray(0);
      } else {
        coordinates = geometry.getJSONArray("coordinates");
      }
      int len = coordinates.length();
      for (int i = 0; i < len; ++i) {
        if (coordinates.get(i) instanceof JSONArray) {
          JSONArray coord = coordinates.getJSONArray(i);
          double lng = coord.getDouble(0);
          double lat = coord.getDouble(1);
          latLngs.add(new LatLng(lat, lng));
        } else {
          double lng = coordinates.getDouble(0);
          double lat = coordinates.getDouble(1);
          latLngs.add(new LatLng(lat, lng));
          break;
        }
      }
    }
    return latLngs;
  }

  private static String readAll(Reader rd) throws IOException {
    StringBuilder sb = new StringBuilder();
    int cp;
    while ((cp = rd.read()) != -1) {
      sb.append((char) cp);
    }
    return sb.toString();
  }
}