Help with java arrays

Question

I have the discipline array and the current array.

The current one is an exact copy of the disciplines. If there are two equal Strings within the disciplines array I need to delete all the same and keep only one.

That is, the current should not contain repeated strings.

Can anyone help with this code?

String coisa = "";
String[] atual = disciplina.clone();;
int conta = 0;
for (int j = 0; j < disciplina.length; j++) {
  if (disciplina[j] != null && nota[j] != 0) {
      if(atual[j].equals(disciplina[j])){
        atual[j] = "";
      }
  }

Answer 1

You can use the Set which does not allow duplicates.

Set<String> disciplinas = new HashSet<>(Arrays.asList(disciplina));

disciplina = disciplinas.toArray(new String[disciplinas.size()]);

---

Set

A Collection that contains no Uplicate Elements. More formally, sets contain no pair of Elements E1 and E2 such that E1.equals(E2), and at Most one null element. As implied by its name, this interface models the Mathematical set abstraction.

In free translation:

A collection that does not contain duplicate items. More formally, sets do not contain pairs of E1 and E2 elements in case of E1.equals(E2). As the name suggests, this interface is an abstraction of the mathematical model "set".

---

A resolution suggestion without using Collection:

public String[] removerDuplicados(String[] base) {
  String[] resultado = new String[base.length];
  int contador = 0;
  boolean encontrado;

  for (int i = 0; i < base.length; i++) {
    String elemento = base[i];

    encontrado = false;

    for (int j = 0; j < resultado.length; j++) {
      if (resultado[j] == null) {
        break;
      }

      if (resultado[j].equals(elemento)) {
        encontrado = true;
      }
    }

    if (!encontrado) {
      resultado[contador] = elemento;
      contador++;
    }
  }

  return Arrays.copyOfRange(resultado, 0, contador);
}

---

Another way is to order the array and then just compare with the previous record to insert into one another, without the duplicates:

public String[] removerDuplicados(String[] base) {
  String[] resultado = new String[base.length];
  String anterior = null;
  int indice = 0;

  Arrays.sort(base);

  for (String atual : base) {
    if (atual != null && (anterior == null || !atual.equals(anterior))) {
      resultado[indice] = atual;
      indice++;
    }

    anterior = atual;
  }

  return Arrays.copyOfRange(resultado, 0, indice);
}

---

Apply the above two methods as follows:

disciplina = removerDuplicados(disciplina);

Answer 2

public static void main(String[] args) {
    String[] a = {"teste1", "teste2", "teste1"};
    String[] b = new String[a.length];
    for(int i = 0; i < a.length; i++) {
        if(arrayNaoContemString(b, a[i])) {
            b[i] = a[i]; 
        }
    }
    for (String string : b) {
        System.out.println(string);
    }
}

public static boolean arrayNaoContemString(String[] array, String string){
   for(String s : array){
       if (string.equals(s)){
           return false;
       }
   }
   return true;
}

See the result in Ideone. Or see this question in SO-en for more solutions.

Answer 3

Try this:

if (!atual.contains(disciplina[j])){
    atual.add(disciplina[j])
}

So in case the array atual does not contain the content of discplina[j] he will add