如何使用不同的对象作为值来实现 Java Hashmap

Question

我想通过 Jackson 解析 YAML 文件，但遇到的问题是其中一个属性（我们称之为“事件”）有一个名为“类型”的字符串和一个“属性”对象，该对象因不同的事件而异。我的问题是我需要为此 YAML 定义 POJO。因此，我想定义一个带有 VariableObject 的 Hashmap，它可以是任何一些预定义的类（为简洁起见，假设为 Shipping 和 Inventory）。我怎样才能实现这样的Hashmap？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;    }}

Answer 1

你说的很简单Object。它是最具体的常见超类：

private static Map<String, Object> properties;

其他解决方案是制作Inventory和Shipping实现一些通用接口，例如Named并将其用作HashMap.

Answer 2

一种方法是制作Shipping和Inventory实现相同的接口（如VariableObject在您的 cas 中）

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;

    }

}