ClassCastException casting error

Question

I'm getting an error on my code and I really dont understand why it's happening:

for(Pacote<Par<String, Double>> pacote : pacotes) /snippet of code where the error occurs/

trying to cast it to

 public class Pacote <E> {

    private int capacidade;
    private ArrayList <E> pacote;

    public Pacote (int capacidade){

        pacote= new ArrayList <> (capacidade);
        this.capacidade=capacidade;
    }


  public Par (A itemA, B itemB){
      this.tipo=itemA;
      this.peso=itemB;
  }

  public A primeiro(){

      return tipo;
  }

  public B segundo () {

      return peso;
  }

}

public class Pacote {

private int capacidade;
private ArrayList <E> pacote;

public Pacote (int capacidade){

    pacote= new ArrayList <> (capacidade);
    this.capacidade=capacidade;
}

public int getCapacidade (){

    return capacidade;
}

public int getNumItems (){

    return pacote.size();
}

public boolean estaCheio () {

    return getNumItems()<capacidade-1;
}

public boolean empacota (E item){
    if (estaCheio())
        return false;
    else { 
        pacote.add(item);
        return true;
    }
       }

public List<E> items(){

   List <E> list = pacote;

   return list;
}

Code around the line it is happening:

public static void main(String[] args) throws IOException {
        // Recebe os dados de input
        Scanner sc = new Scanner(System.in);
        System.out.println("Introduza o ficheiro com a lista de items a empacotar:");
        String fich = sc.nextLine();
        BufferedReader reader = new BufferedReader(new FileReader(fich));
        System.out.println("Introduza a capacidade dos pacotes:");
        int capacidade = Integer.parseInt(sc.nextLine());

        // Cria os pacotes
        List<Pacote<Par<String, Double>>> pacotes = 
                GestorPacotes.criaPacotes(reader, capacidade);
        reader.close();

        // Mostra a informacao dos pacotes
        System.out.println("Pacotes formados:");
        int index = 0;
        for(Pacote<Par<String, Double>> pacote : pacotes) {  /error here/
            System.out.println("Pacote " + index++ + ":");

And I'm getting "Exception in thread "main" java.lang.ClassCastException: pack.Par cannot be cast to pack.Pacote", not sure why. Can someone help?

 public static List<Pacote<Par<String, Double>>> criaPacotes(
BufferedReader fileReader, int capacidadePacotes)
throws IOException {
        List retorno = new ArrayList <> (6);
        String s;
        while ((s=fileReader.readLine())!=null){
            retorno.add(parseItem(s));
        }
        return retorno;

    }

Answer 1

Your declaration of Par is incorrect. I suppose you want it to be an inner class, but you haven't declared it as class.

public Par (A itemA, B itemB){
  this.tipo=itemA;
  this.peso=itemB;
}

This is a constructor, but it is treated as constructor to the surrounding class, with is Pacote , not Par , so you do not actually have a class Par ...