Sequential list implementation exercise

Question

I’m trying to solve this college exercise that I’ve already implemented a lot of, but there are still three things missing. It’s about data structure with Java OO - sequential list.

Follow the code of the list class:

public class ListaSequencial {
    private Contato [] contatos = new Contato[10];
    private int n = 0;


    boolean isVazia(){
        return n == 0;
    }

    boolean isCheia(){
        return n == contatos.length;
    }

    int tamanho(){
        return n;
    }

    private void deslocaDireita(int pos){
        for(int i = n; i > pos;i--){
            contatos[i] = contatos[i - 1];
        }
    }

    boolean inserir(Contato contato){
        if(isCheia()){
            return false;
        }

        contatos[n] = contato;
        n++;
        return true;

    }
    boolean inserir(Contato c, int pos){
        if(isCheia()){
            return false;
        }
        deslocaDireita(pos);
        contatos[pos] = c;
        n++;
        return true;
    }

    private void deslocaEsquerda(int pos){
        for(int i = pos; i < n - 1 ;i++){
            contatos[i] = contatos[i+1]; 
        }
    }

    boolean remover(int pos){

        if(pos < 0 || pos >=n){
            return false;
        }
        deslocaEsquerda(pos);
        n--;
        return true;
    }


    public String imprimir(){
        String str = "";
        if(isVazia()){
            return "lista vazia";
        }
        else{
            for(int i = 0; i < n; i++){
                str += contatos[i].nome + " - " + contatos[i].telefone + "\n";   
            }
            return str;
        }
    }


    Contato buscar(int pos){
        if(pos < 0 || pos >= n){
            return null;
        }
        return contatos[pos];
    }

    int getPosicao(Contato contato){

        for(int i = 0; i < n; i++){
            if(contatos[i] == contato){
                return i;
            }
        }
        return -1;
    }
}

What I don’t know and need for Exercise:

1. I need to create a method to concatenate 2 lists;

2. I need to create a method that once the list fills, create a larger container (vector) so it never fills (like a loop);

3. Finally, I need a method to remove an element from the list by passing instead of the index, the element itself. In the case, remove the first occurrence found.

Somebody give me a hand?

Answer 1

(3) This is the easiest one. Do the following:

• Create the new method to delete the element, the return is boolean.

• Scroll through the array using a for. The elements to be covered are from 0 to < n.

• Check inside your is if affixing the corresponding array has the element you are looking for. If you have, use the remover(int) to remove this position and return true right away.

• To decide if the element found is what you are looking for or not, I recommend using the method java.util.Objects.equals(Object a, Object b).

• If you have finished going through the array and do not find the element, return false.

(2) Growing the list is the most complicated of the three. Do the following:

• Do the method isCheia() be private. The reason for this is that from the external point of view of the class, the list never gets full, since when it fills up, it will increase and no longer remain full, and therefore this method would no longer make sense to those who are looking at the outside class.

• Create a private method crescer(), which is responsible for making the internal array grow in size. For this you create an array larger than the old one, copy all the elements and exchange the reference (contatos = novoArray;).

• Instead of if (isCheia()) { return false; }, do if (isCheia()) { crescer(); }.

• The methods inserir return void.

(1) To create the method that concatenates two lists do this:

• This item is much easier if you have done part 2 first. Before implementing item 1, do item 2.

• Create a static method that takes the two lists as a parameter and returns a list.

• This method creates a new list. Scrolls through the lista1.n elements from the first list and add them to the new list. Then it traverses the lista2.n elements of the second list and does the same thing.

• Return the new created list.