reverseOrder() In java not reversing

Question

I have a method in java to sort a vector in a decreasing method, but when I run the test it returns me the unpaired vector.

Follows the Method:

public void sort() {
  int vet[] = this.vetor;
  inverter(vet);
}

private void inverter(int[] vet) {

  Integer[] vet_x = new Integer[vet.length];
  for (int i=0; i < vet.length; i++){
      vet_x[i] = new Integer(vet[i]);
  }
  Arrays.sort(vet_x, Collections.reverseOrder());
}

The this.vetor is being generated by the function .random() in the test file

 int[] vetor = geraVetor.random(100);

When I test function:

@Override
public void sort() {
  int vet[] = this.vetor;
  inverter(vet);
}

private void inverter(int[] vet) {
 Arrays.sort(vet);
}

He’s ordering straight up in ascending order.

The function that prints the vector is this:

 public void Ordenacao() {
    GeraVetor geraVetor = new GeraVetor();

    // Crio um novo vetor
    int[] vetor = geraVetor.random(100);

    // Faço uma cópia dele
    int[] experado = Arrays.copyOf(vetor, vetor.length);

    // Ordeno a cópia com uma ordenação do Java
    //Arrays.sort(experado);

    // Teste de Ordenação
    Ordena ordena = new Ordena(vetor);
    ordena.sort();

    System.out.println("Ordenado: " + ordena.toString());
    System.out.println("Experado: " + Arrays.toString(experado));

    Assert.assertArrayEquals(experado, ordena.get());
}

Answer 1

You can do it:

private void inverter(int[] vet) {
    Integer[] vet_x = new Integer[vet.length]; // Copia criada, ...
    for (int i = 0; i < vet.length; i++) {
        vet_x[i] = vet[i]; // ... preenchida, ...
    }
    Arrays.sort(vet_x, Collections.reverseOrder()); // ... e ordenada.
    for (int i = 0; i < vet.length; i++) {
        vet[i] = vet_x[i]; // Copiando de volta para o original.
    }
}

That is, after ordering vet_x, copy the values back to vet.

Note that you do not need to use new Integer (even, to do this is deprecated since Java 9). With direct attribution, the compiler does the autoboxing alone.