Instantiate objects by configuration file on java

Question

I have this object:

public class TheObjectToInstantiate{
 public String Name;
 public String Surname;
 public TheObjectToInstantiate(){
 }
}

I want to instantiate an array of TheObjectToInstantiate[] with configuration file:

TheObjectToInstantiate1.Name="Pippo"
TheObjectToInstantiate1.Surname="PippoSurname"
TheObjectToInstantiate2.Name="Pluto"
TheObjectToInstantiate2.Surname="PlutoSurname"

I've tried with

public ConfigReader(){
    Properties prop = new Properties();
    InputStream input = null;

    try {

        input = new FileInputStream("configuration.prop");
        prop.load(input);

        Enumeration<?> e = prop.propertyNames();
        while (e.hasMoreElements()) {
            String key = (String) e.nextElement();
            String value = prop.getProperty(key);
            ......
        }

    } catch (IOException ex) {
        ex.printStackTrace();
    } finally {
        if (input != null) {
            try {
                input.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

}

scanning all properties and instatiate object manually.

There are ways or open source wrapper to do this without manually compare all properties? Thanks

Answer 1

It's easier to use json files and deserialize them with libraries like Jackson. You may also check http://www.mkyong.com/java/how-to-convert-java-object-to-from-json-jackson and How to use Jackson to deserialise an array of objects

public class TheObjectToInstantiate {
    public String Name;
    public String Surname;
    public TheObjectToInstantiate(){}
}

public class JacksonExample {
    public static void main(String[] args) {

    ObjectMapper mapper = new ObjectMapper();

    try {
        // Convert JSON string from file to Object
        TheObjectToInstantiate object = mapper.readValue(new File("G:\\myobject.json"), TheObjectToInstantiate.class);
    } catch (IOException e) {
            e.printStackTrace();
    }

}

json file would be like this:

{
  "Name" : "foo",
  "Surname" : "bar"
}

you can also deserialize a list of objects:

List<TheObjectToInstantiate> myObjects = mapper.readValue(new File("G:\\myobjectlist.json"), new TypeReference<List<TheObjectToInstantiate>>(){});


[{
    "Name" : "foo1",
    "Surname" : "bar1"
},
{
    "Name" : "foo2",
    "Surname" : "bar2"
}]

It also supports more complex structures like nested objects or a List or array of other objects inside your primary object.