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francesco14
Asked: 2022-03-27 11:24:30 +0800 CST 2022-03-27 11:24:30 +0800 CST

How to access attribute inside object inside collection

  • 772

I have a problem when it comes to finding a book object through an attribute (isbn) in a collection, I have the attribute to compare but I can't access the same attribute of the objects in my collection, I don't add more implementation to simplify the doubt as much as possible, it throws me this error ( The type of the expression must be an array type but it resolved to ArrayList of books ) please, how could I do the type conversion to have the correct if() expression?:

    ArrayList<Libro> coleccion1 = new ArrayList<Libro>();
    Libro libro = new Libro();
    for (int i = 1; i <= 5; i++) {
        libro.crearLibro();
        coleccion1.add(libro);
        
    }
        socketAlCliente = socketServidor.accept();
        System.out.println("Petición número: "+ peticiones);
        entrada = new InputStreamReader(socketAlCliente.getInputStream());
        BufferedReader bf = new BufferedReader(entrada);
    
String librorecibido = bf.readLine();
int isbnrecibido = Integer.parseInt(librorecibido);
                for (int i = 0; i < coleccion1.size(); i++) {
                    if(isbnrecibido == coleccion1[i].getisbn) {
                        
                }
java

1 Answers

  1. Best Answer

    It's actually coleccion1a ArrayListso to access its elements use the method get()and the element's index, assuming your object Librohas a "getter" called getisbn(), you can get the value like this:

    coleccion1.get(indice).getisbn()

    This would be applying it to your code:

    for (int i = 0; i < coleccion1.size(); i++) {
      //if(isbnrecibido == coleccion1[i].getisbn) {
      if(isbnrecibido == coleccion1.get(i).getisbn()) {

      //Es igual!                

     }
}
    • 0