How to arrange products according to price?

I have tried multiple ways to arrange products according to their price from low to high but the program keeps showing error

class string/int has no method sort

I want to arrange the products list according to price and weight.

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';

import 'ProductModel.dart';


class ProductScreen extends StatefulWidget {
  final ValueSetter<ProductModel> _valueSetter;
  final ValueSetter<ProductModel>_valueRemoval;
  static bool name=false;
  ProductScreen(this._valueSetter,this._valueRemoval);

  @override
  _ProductScreenState createState() => _ProductScreenState();
}

class _ProductScreenState extends State<ProductScreen> {


  //Seller s=new Seller(myController, myController1, myController2, imageFile);


 final List<ProductModel> products = [
    ProductModel("A cow1", 300,"24",Image.network("https://images.unsplash.com/photo-1570042225831-d98fa7577f1e?ixlib=rb-1.2.1&w=1000&q=80")),
    ProductModel("C cow2", 400,"43",Image.network("https://images.unsplash.com/photo-1570042225831-d98fa7577f1e?ixlib=rb-1.2.1&w=1000&q=80")),
    ProductModel("B cow3",600,"67",Image.network("https://images.unsplash.com/photo-1570042225831-d98fa7577f1e?ixlib=rb-1.2.1&w=1000&q=80")),
    ProductModel("E cow4", 1000,"123",Image.network("https://images.unsplash.com/photo-1570042225831-d98fa7577f1e?ixlib=rb-1.2.1&w=1000&q=80")),
    ProductModel("D cow5", 900,"150",Image.network("https://images.unsplash.com/photo-1570042225831-d98fa7577f1e?ixlib=rb-1.2.1&w=1000&q=80")),
    ProductModel("F cow6",1200,"189",Image.network("https://images.unsplash.com/photo-1570042225831-d98fa7577f1e?ixlib=rb-1.2.1&w=1000&q=80")),
   //ProductModel(Seller.myController.text,int.parse(Seller.myController2.text),Seller.myController1.text,Image.file(Seller.imageFile),),
    //myController etc are static memebers in sellers because only static members can be use in initializers of productModel
    //Use classname.parameter because you can't acces static members through object of class like s.myController.text would be wrong

  ];
  List<ProductModel> productsArranged=[];
  

 filterByPrice(products) {
   setState(() {
     ProductScreen.name=true;
     /*()productsArranged= products
         .where((products) =>
         (products.name).toLowerCase().contains(products.toLowerCase()))
         .toList(); */


   });
 }

 SortPrice(products){
   products.sort((a,b)=>a.compareTo(b));
 }



  @override
  Widget build(BuildContext context) {
    return Container(
      child:ListView.separated(
        itemBuilder: (context, index){
          return ListTile(
           title:Text(products[index].name),
              leading:products[index].i,
              subtitle:Column(
                children:<Widget>[
                  !ProductScreen.name?Text("\$${products[index].price}", 
                    style: TextStyle(color: Colors.redAccent, fontSize: 20, fontWeight: FontWeight.w500),):SortPrice(products[index].price),
                  //Text(,style: TextStyle(color: Colors.redAccent, fontSize: 20, fontWeight: FontWeight.w500),),
                //Text("\$${products[index].price}",style: TextStyle(color: Colors.redAccent, fontSize: 20, fontWeight: FontWeight.w500),),
                  
                  Text(products[index].weight.toString()+" kg",
                  style: TextStyle(color: Colors.redAccent, fontSize: 20, fontWeight: FontWeight.w500),),
                     // SortPrice(products[index].weight),

                  

                  Row(
                    mainAxisAlignment: MainAxisAlignment.end,
                    children: <Widget>[


                      IconButton(
                        icon: Icon(Icons.remove_circle, color: Colors.green,),
                        onPressed: () {
                          widget._valueRemoval(products[index]);
                          SnackBar s = SnackBar(content: Text(
                              products[index].name + " removed from your cart"),
                            duration: Duration(milliseconds: 3),
                            backgroundColor: Colors.pinkAccent,);
                          Scaffold.of(context).showSnackBar(s);
                        },),


                      IconButton(icon: Icon(Icons.add_circle, color: Colors.red,),
                        onPressed: () {
                          widget._valueSetter(products[index]);
                          SnackBar s = SnackBar(content: Text(
                              products[index].name + " added to your cart"),
                            duration: Duration(milliseconds: 3),
                            backgroundColor: Colors.cyanAccent,);
                          Scaffold.of(context).showSnackBar(s);
                        },),


                    ],),

                ], ),

              onTap: (){

              },

          //  ),
          );
        },
        separatorBuilder: (context, index){
          return Divider();
        },
        itemCount: products.length
    ),);
  }
}

The below code is my ProductModel

import 'package:flutter/cupertino.dart';

class ProductModel{

    String name;
    int price;
    String weight;
    Image i;
    ProductModel(this.name,this.price,this.weight,this.i)
}