Migrating package to null-safety

example/main.dart

@@ -1,3 +1,5 @@
+// ignore_for_file: unused_element
+
 import 'package:flutter/material.dart';
 import 'package:flutter_particles/particles.dart';
 
@@ -26,7 +28,7 @@ class MyApp extends StatelessWidget {
 }
 
 class MyHomePage extends StatefulWidget {
-  MyHomePage({Key key, this.title}) : super(key: key);
+  MyHomePage({Key? key, this.title}) : super(key: key);
 
   // This widget is the home page of your application. It is stateful, meaning
   // that it has a State object (defined below) that contains fields that affect
@@ -37,7 +39,7 @@ class MyHomePage extends StatefulWidget {
   // used by the build method of the State. Fields in a Widget subclass are
   // always marked "final".
 
-  final String title;
+  final String? title;
 
   @override
   _MyHomePageStateCustom createState() => new _MyHomePageStateCustom();
@@ -72,4 +74,4 @@ class _MyHomePageStateCustom extends State<MyHomePage> {
       ),
     );
   }
-}
+}

lib/draw_particles.dart

@@ -2,9 +2,9 @@ import 'package:flutter/material.dart';
 import 'package:flutter_particles/particle.dart';
 
 class DisplayPoints extends CustomPainter {
-  final List<Particle> particlesList;
+  final List<Particle>? particlesList;
 
-  final double strokeSize;
+  final double? strokeSize;
 
   DisplayPoints({
     this.particlesList,
@@ -15,26 +15,26 @@ class DisplayPoints extends CustomPainter {
   void paint(Canvas canvas, Size size) {
     Paint line = new Paint();
     line.strokeCap = StrokeCap.round;
-    line.color = particlesList.elementAt(0).color;
+    line.color = particlesList!.elementAt(0).color!;
 
     // Draw all the particles
-    for (var particle in particlesList) {
-      line.strokeWidth = particle.size;
+    for (var particle in particlesList!) {
+      line.strokeWidth = particle.size!;
       Offset center = new Offset(particle.xCoor, particle.yCoor);
       line.style = PaintingStyle.fill;
-      canvas.drawCircle(center, particle.size, line);
+      canvas.drawCircle(center, particle.size!, line);
     }
 
     // Draw the connect line
-    for (int i = 0; i < this.particlesList.length; i++) {
-      for (int j = i + 1; j < this.particlesList.length; j++) {
-        Particle particle = this.particlesList.elementAt(i);
-        Particle anotherParticle = this.particlesList.elementAt(j);
+    for (int i = 0; i < this.particlesList!.length; i++) {
+      for (int j = i + 1; j < this.particlesList!.length; j++) {
+        Particle particle = this.particlesList!.elementAt(i);
+        Particle anotherParticle = this.particlesList!.elementAt(j);
         if (particle.isNear(anotherParticle)) {
           Offset firstParticle = new Offset(particle.xCoor, particle.yCoor);
           Offset secondParticle =
               new Offset(anotherParticle.xCoor, anotherParticle.yCoor);
-          line.strokeWidth = strokeSize;
+          line.strokeWidth = strokeSize!;
           canvas.drawLine(firstParticle, secondParticle, line);
         }
       }

lib/particle.dart

@@ -1,25 +1,27 @@
+// ignore_for_file: unnecessary_statements
+
 import 'dart:math';
 
 import 'package:flutter/material.dart';
 
 class Particle {
-  final Color color;
-  double xCoor;
-  double yCoor;
-  final double size;
-  double xDirection;
-  double yDirection;
-  static double widgetWidth;
-  static double widgetHeight;
+  final Color? color;
+  final double yCoor;
+  final double xCoor;
+  final double? size;
+  late double xDirection;
+  late double yDirection;
+  static late double widgetWidth;
+  static late double widgetHeight;
   double connectDistance;
   Random random = new Random();
   double minSpeed;
   double maxSpeed;
 
   Particle({
     this.color,
-    this.xCoor,
-    this.yCoor,
+    required this.xCoor,
+    required this.yCoor,
     this.size,
     this.connectDistance = 100.0,
     this.minSpeed = 0.1,
@@ -54,8 +56,8 @@ class Particle {
         this.yCoor + this.yDirection < 0) {
       this.yDirection = this.yDirection * (-1);
     }
-    this.xCoor += this.xDirection;
-    this.yCoor += this.yDirection;
+    this.xCoor + this.xDirection;
+    this.yCoor + this.yDirection;
   }
 
   double doubleInRange(double start, double end) =>

lib/particles.dart

@@ -27,11 +27,11 @@ class Particles extends StatefulWidget {
 
 class ParticlesState extends State<Particles>
     with SingleTickerProviderStateMixin {
-  Animation animation;
-  AnimationController animationController;
+  Animation? animation;
+  late AnimationController animationController;
   Random random = new Random();
 
-  List<Particle> particlesList = new List();
+  List<Particle> particlesList = [];
 
   void addToParticlesList() {
     for (int i = 1; i <= widget.numParticle; i++) {

pubspec.yaml

@@ -11,7 +11,7 @@ homepage: https://github.com/Aleadinglight/Flutter-Particles
 version: 1.0.0+8
 
 environment:
-  sdk: ">=2.0.0-dev.68.0 <3.0.0"
+  sdk: '>=2.12.0 <3.0.0'
 
 dependencies:
   flutter: