SQL查询的返回方法

Question

Good afternoon guys, I created a query for the return of sql but I can not change the return to return it Next, I can return return the query inside the method but if I want to pick the method to add a combobox or to work with the returned value I can not only return it inside the method.

How can I change this method to use a return?

private void onClickLocalizarCidadePorEstado() throws Exception {
        CidEstController cc = new CidEstController();
        try {
            List<Cidade> c = cc.buscaCidadePorEstado(uf);
            for(Cidade cidade : c)
                System.out.println(cidade.getNom_cidade());
        } catch (SQLException e) {
            JOptionPane.showMessageDialog(this, "Ocorreu um erro, tente novamente!n" +
                            e.getLocalizedMessage()
                    );
        } catch (NullPointerException e){
            JOptionPane.showMessageDialog(this, "Contato n&atilde;o localizdo ou n&atilde;o existe!n" + 
                            e.getLocalizedMessage()
                    );
        }
    }

Answer 1

Change the method's return type from void to List<Cidade> , then replace the for loop with return c; . (You could also remove the c variable and just do return cc.buscaCidadePorEstado(uf) .)

You'll still need to return something even when an exception occurs. You could put return null; within each of your catch blocks, or return Collections.emptyList() if you don't want the calling method to have to check for null results. Alternatively, you could throw a different exception type instead — for example, throw new CityLookupException(e); . (You'd need to create that class, of course.)