Prevent database insertion with String " (with space in name)

Question

My problem is this::

I have a Jtextfield that will receive the name of my entity, will pass to the controller, which will create the bean and finally, call the DAO to insert into the bank. Simple thing a basic CRUD.

The table field in the database is NOT NULL, because it wouldn’t make sense to be blank.

Thinking about: Make It Simple! I did the following in the method that will be responsible for the events in Jdialog, I will have the empty spaces of the name start and use a Joptionpane if Jtextfield is empty.

However we will also be evaluated by the elegance of the code, better ways to solve the problems, for example using Pattern. Following this logic in the controller’s method, responsible for instantiating the DAO and inserting in the database a Boolean return only, to warn the method that called whether or not the insertion was successful. In this case, the method will check if the entity name is null, and if there is an equal name already registered in the database, instantiating an Arraylist with all registered names and using a Foreach for verification, if the name already exists returns false.

But, as I said, we will be judged by the elegance of the code, so imagine making an exception and treating it back if the method returns false. Seeking more information I read:

How to best treat exceptions in Java?
It is good practice to make an exception in such cases?
Exception vs Runtimeexception, when using one or the other?

And some other things more for my better understanding that cleared up a little, but, I still have the doubt: This way is correct or would be more, say "elegant", treat as an exception?

Codes:

Save button method:

public void setupEvents() {
    btnSave.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent e) {
            tfNameNewDiscipline.getText().trim();
            ControllerDiscipline controller;

            if(tfNameNewDiscipline.getText().isEmpty())
                JOptionPane.showMessageDialog(null, "Digite um nome para a Disciplina", "Erro no cadastro da Disciplina", JOptionPane.ERROR_MESSAGE);
            else  {
                controller = new ControllerDiscipline();
                if(controller.addDiscipline(tfNameNewDiscipline.getText()) == false)
                    JOptionPane.showMessageDialog(null, "Disciplina já existe", "Erro no cadastro da Disciplina", JOptionPane.ERROR_MESSAGE);
            }
        }
    });

Method of the controller class you add to the database:

public boolean addDiscipline(String name) {

    DisciplineDAO dao = new DisciplineDAO();
    Discipline entity = new Discipline();

    entity.setName(name);

    if (entity.getName().isEmpty()) {
        return false;
    }

    ArrayList<Discipline> disciplines = new ArrayList<>();
    disciplines.addAll(dao.searchData());

    for(Discipline discipline : disciplines) {
        if(entity.getName().equals(discipline.getName()))
            return false;
    }

    dao.insert(entity);
    return true;
}

Answer 1

Friendly talk!

About the exceptions: I haven’t found anywhere the launch or capture of Exceptions.. Is it really implemented? Even though you’re being judged for the elegance of the code, I think exaggeration treat validations of view with Exceptions. I find it much more valid to treat your business rule validations (Business or Controller layer: depends on how you are implementing right hehe) with Exceptions than View.

On the validation of " ": I usually use the class StringUtils package org.apache.commons.lang3 to make that kind of validation. She has (if I’m not mistaken), a method called isNotNullOrEmpty() that works that is a beauty! :)

I hope I’ve helped!