How to implement a Java Hashmap with different objects as values

Question

I want to parse a YAML-file via Jackson but encounter the problem that one of the properties (let's call it 'Event') has a string called 'type' and a 'properties' object that differs for different Events. My issue is that I need to define the POJOs for this YAML. Therefore, I want to define a Hashmap with VariableObject that can be any of some predefined classes (for brevity, let's say Shipping and Inventory).

How can I implement a Hashmap like that?

public class Event {
    private static String type;
    private static Map<String, VariableObject> properties;

    public static void main(String[] args) {
        Inventory inventory = new Inventory("inventoryName", 13);
        properties.put("Inventory", inventory);
        Shipping shipping = new Shipping("shippingName", true);
        properties.put("Shipping", shipping);
    }
}


public class Inventory {

    private static String name;
    private static int someNumber;

    public Inventory(String name, int someNumber) {
        this.name = name;
        this.someNumber = someNumber;
    }
}


public class Shipping {

    private static String name;
    private static boolean someBoolean;

    public Shipping(String name, boolean someBoolean) {
        this.name = name;
        this.someBoolean = someBoolean;
    }
}

You should use either a common interface or super class, i.e. Inventory implements VariableObject or Inventory extends VariableObject (since both have a name property that could be part of the common super class VariableObject and thus it would be Inventory extends VariableObject). — Thomas
– Thomas, Commented Apr 18, 2019 at 14:22

Andronicus · Accepted Answer · 2019-04-18 14:21:10Z

3

What you're talking ablut is simple Object. It's the most specific common superclass:

private static Map<String, Object> properties;

Other solution would be to make Inventory and Shipping implement some common interface, for example Named and use it as type parameter in HashMap.

answered Apr 18, 2019 at 14:21

Andronicus

26.2k18 gold badges55 silver badges92 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Mathiewz · Accepted Answer · 2019-04-18 14:21:46Z

One way to do this is to make Shipping and Inventory implements the same interface (like VariableObject in your cas)

public class Event {
    private static String type;
    private static Map<String, VariableObject> properties;

    public static void main(String[] args) {
        Inventory inventory = new Inventory("inventoryName", 13);
        properties.put("Inventory", inventory);
        Shipping shipping = new Shipping("shippingName", true);
        properties.put("Shipping", shipping);
    }
}

public interface VariableObject{
//you can define common methods here if you want
}


public class Inventory implements VariableObject{

    private static String name;
    private static int someNumber;

    public Inventory(String name, int someNumber) {
        this.name = name;
        this.someNumber = someNumber;
    }
}


public class Shipping implements VariableObject{

    private static String name;
    private static boolean someBoolean;

    public Shipping(String name, boolean someBoolean) {
        this.name = name;
        this.someBoolean = someBoolean;
    }
}

Collectives™ on Stack Overflow

How to implement a Java Hashmap with different objects as values

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related