How to clean whitespaces in jComboBox

Question

I´m trying to make a jComboBox that contains books titles and when i hit a button that "loan a book", that book no longer appear. I was able to make all that work, but when I "lend a book", there is a blank space where it was located. This is the code that i tryied:

    private void cargarLibros()
    {
        String[] libros = new String[this.librosDisponibles()]; //librosDisponibles() returns the amount of books available
        for(int i=0; i<this.librosDisponibles(); i++)
        {
            if(!(this.getBiblioteca().getLibros().get(i).prestado()))
            {
                libros[i] = this.getBiblioteca().getLibros().get(i).getTitulo(); //get the titles
            }
        }
    jComboBox3.removeAll();
    DefaultComboBoxModel modelo = new DefaultComboBoxModel(libros);
    this.jComboBox3.setModel(modelo);
}

And also tryied this:

    private void cargarLibros()
    {
        String[] libros = new String[this.librosDisponibles()];
        for(int i=0; i<this.librosDisponibles(); i++)
        {
            if(!(this.getBiblioteca().getLibros().get(i).prestado()))
            {
                libros[i] = this.getBiblioteca().getLibros().get(i).getTitulo();
            }
        }
        DefaultComboBoxModel modelo = (DefaultComboBoxModel)jComboBox3.getModel();
        modelo.removeAllElements();
        for(String libro : libros)
        {
            modelo.addElement(libro);
        }
        jComboBox3.setModel(modelo);
}

With both of them i obtain this results:

Picking a book

Borrowed book

Answer 1

and when i hit a button that "loan a book", that book no longer appear.

You need to remove the selected item from the model of the combo box.

So the code in your ActionListener of the combo box would be something like:

JComboBox comboBox = (JComboBox)e.getSource();
DefaultComboBoxModel model = (DefaultComboBoxModel)comboBox.getModel();
Object item = comboBox.getSelectedItem();
model.removeElement( item );