Ankit-Slnk

import android.content.Context;
import android.content.SharedPreferences;
import com.google.gson.Gson;

public class ComplexPreferences {

    private static ComplexPreferences complexPreferences;
    private Context context;
    private SharedPreferences preferences;
    private SharedPreferences.Editor editor;

Ankit-Slnk

static String calculateDistance(double lat1, double lon1, double lat2, double lon2) {
    var p = 0.017453292519943295;
    var c = cos;
    var a = 0.5 - c((lat2 - lat1) * p) / 2 + c(lat1 * p) * c(lat2 * p) * (1 - c((lon2 - lon1) * p)) / 2;
    double distance = 12742 * asin(sqrt(a));
    String strDistance = distance.toStringAsFixed(2);
    return strDistance + " km";
}

Ankit-Slnk

static bool isValidEmail(String email) {
    return RegExp(r"^[a-zA-Z0-9.a-zA-Z0-9.!#$%&'*+-/=?^_`{|}~]+@[a-zA-Z0-9]+\.[a-zA-Z]+").hasMatch(email);
}

static bool isValidName(String name) {
    return !name.contains(RegExp(r"[0-9!@#$%^&*()_+\-=\[\]{};':\\|,.<>\/?]"));
  }

  static bool isSpecialCharacter(String name) {
    return RegExp(r"[!@#$%^&*()_+\-=\[\]{};':\\|,.<>\/?]").hasMatch(name);

Ankit-Slnk

import 'package:rxdart/rxdart.dart';
class SampleBloc {
  
  static final SampleBloc _singletonBloc = new SampleBloc._internal();
  
  final sampleBlocObj = BehaviorSubject<int>();
  
  factory SampleBloc() {
    return _singletonBloc;
  }

Ankit-Slnk

static LatLngBounds getBounds(List<LatLng> polylineCoordinates) {
    double x0, x1, y0, y1;
    for (LatLng latLng in polylineCoordinates) {
      if (x0 == null) {
        x0 = x1 = latLng.latitude;
        y0 = y1 = latLng.longitude;
      } else {
        if (latLng.latitude > x1) x1 = latLng.latitude;
        if (latLng.latitude < x0) x0 = latLng.latitude;
        if (latLng.longitude > y1) y1 = latLng.longitude;