Recover the value of an attribute of a generic object in Java

Question

I’m making a system where I read Java objects of different types of XML files. So I don’t have a single object type and consequently I don’t know its attributes or methods. I would like to perform a search, in which I entered a string indicating attribute and value, and this search returned to me all objects that had this attribute and that was equal to the value in a ArrayList.

Example: I have some XML files, of the types Produto, Pessoa and Carro, are already read and instantiated. I want to look for objects that have the following feature ano: 1996, the classes Produto and Carro has the attribute ano, however Pessoa he doesn’t have it. It would traverse the objects, where it would be analyzed if the value is equal and would take the necessary steps, if the attribute did not exist it would return null or a Exception to be treated.

Someone has an idea of how I can do this recovery, the biggest problem is who can be objects of different types, is that a non-relational bank job, if it were relational would be very easy, with defined types.

I’d like something that as a .getAtributte (String nomeAtributo, Object o), where the former is an attribute name and the latter the object analyzed.

Answer 1

From a single entity, for example Entidade, you will need to have inside her a Map<String, Object> mapa.

To each value obtained from xml, vc will assign to the object used mapa.put(colunaXml, valorColunaXml).

His method getAttribute(String coluna) should follow the pattern

for (Map.Entry<String, Object> entry : mapa.entrySet()) {
    if(entry.getKey().equals(coluna.toString()){
        return entry.getValue();
    }
}

Answer 2

Create an Objetoxml class that will be common to all of them.

Within Objetoxml, you can place a dynamic structure as a Chained List and when creating the object, you populate the list with the objects you received from the database.

In Objetoxml, you then create the method: o. getAtributte (String names tribute)

Which will basically go through the list of attributes and answer the value if it exists, or null if the attribute does not exist in the list.