Locating Object in a List

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1

I have the following objects

    public class Passo {
      private Long id;
      private Date dataAtend;
      private Time horaRealizada;
      private Long idProfissionalRealizador;
      private String Descricao;
      /*getter & Setters*/  
    }

    public class Atendimento
    {
      private Long id;
      private Date dataAtend;
      private Long idPaciente;
      private Long idProfissionalResponsavel;
      private List<Passo> passos;

      /*getter & Setters*/ 
      public void addPasso(Passo passo){
        passos.add(passo)
      }

    }

and I have a list of Calls, where I have to locate a call by your ID, on this list, and insert more Steps. Something like that

    ...{
      List<Atendimento> atd = new ArrayList<Atendimento>();
      int idAtendimento;
      Passo passo;
      /* Trecho de codigo*/
      int index = atd.indexOf(atd.element.id = idAtendimento);
      if (index > 0 )
      {
        Atendimento(atd.get(index)).addPasso(passo);    
      }  
      else
      {
        Atendimento atend =util.GetAtendimento(idAtendimento);
        atend.addPasso(passo);
        atd.add(atend);
      }
    }

I cannot overwrite the equals, because it is already overwritten comparing all values... =/

java list arraylist

  • Public Class Passo - You know that the public and the class should be in lower case, right?

  • Correct, Victor. =)

  • Simply make a for who searches the list for an element that contains the desired id and returns that element or null case not found does not solve for you?

  • Dude, I don’t understand your example. The chunk of code you gave doesn’t compile or filling what is missing in an imaginative way, because in the line int index = atd.indexOf(atd.element.id = idAtendimento); the idAtendimento is an uninitialized variable. In addition, the assignment within the indexOf seems to me very suspicious and confused. Also, Atendimento(atd.get(index)) also does not compile because Atendimento is a class, not a method. Also, you don’t know what it is util.GetAtendimento.

2 answers

3


That doesn’t work here?

private List<Atendimento> lista = new ArrayList<>();

private Atendimento buscarPorId(long id) {
    for (Atendimento a : lista) {
        if (a.getId().longValue() == id) return a;
    }
    return null;
}

private void adicionarPasso(long idAtendimento, Passo passo) {
    Atendimento a = buscarPorId(idAtendimento, lista);
    if (a == null) {
         a = fazerAlgumaCoisaQueCrieOuObtenhaOAtendimentoComEsteId(idAtendimento);
         lista.add(a);
    }
    a.addPasso(passo);
}

Another idea is to use one Map instead of a List, to avoid having to scroll through the list to find an element. This would be:

private Map<Long, Atendimento> map = new TreeMap<>();

private void adicionarPasso(long idAtendimento, Passo passo) {
    Atendimento a = map.get(idAtendimento);
    if (a == null) {
         a = fazerAlgumaCoisaQueCrieOuObtenhaOAtendimentoComEsteId(idAtendimento);
         map.put(idAtendimento, a);
    }
    a.addPasso(passo);
}

If you need to convert the List for Map at some point, you can use this:

private static Map<Long, Atendente> mapear(List<Atendimento> lista) {
    Map<Long, Atendente> map = new TreeMap<>();
    for (Atendimento a : lista) {
         map.put(a.getId(), a);
    }
    return map;
}

If you need to convert the Map for a List:

List<Atendimento> lista = new ArrayList<>(map.values());

Or else, if you prefer to convert without creating defensive copy, you can also use it like this:

Collection<Atendimento> lista = map.values();

0

Take a look in this material about Comparator and Comparable, of Caelum. With it you can define the attribute id of your object as a parameter for comparison.

I hope it will help the material (was my reference when I needed this type of technique =D)

Hug

  • the problem is that I don’t want to sort, but get the class. but at the end of this article has a link to another that seems more interesting. I think he’s more useful to me

  • Just create a method that will use the compareTo and when equal, return the selected object in comparison. I believe that this way does not bring you so much work in the implementation.

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