CODEWITHSUNDEEP
javaenumsjava-stream
Suman
Suman

Reputation: 868

Convert Enum with attributes to map in Java

I have an enum as below:

@AllArgsConstructor
public enum EnumExample {
    VAL1("val1 description", 100),
    VAL2("val2 description", 200);

    String description;
    int value;
}

Now I want to return all enum values with attributes as a list of the map as below:

[
  {
    "name": "VAL1",
    "description": "val1 description",
    "value": 100
  },
  {
    "name": "VAL2",
    "description": "val2 description",
    "value": 200
  }
]

I am able to achieve this using the below code:

Arrays.stream(EnumExample.values())
      .map(enumExample -> 
              ImmutableMap.of("name", enumExample.name(),
                              "description", enumExample.description,
                              "value", enumExample.value))
      .collect(Collectors.toList())

But I want to know if there any best way to achieve the same without explicitly converting EnumExample to Map. If any new attribute gets added then it should be coming in the resulting map as a new K, V pair.

I tried the below ways but both return only enum values [VAL1, VAL2].

Tried to convert to map too but returns {"VAL2":"VAL2","VAL1":"VAL1"}.

Arrays.stream(EnumExample.values())
      .collect(Collectors.toMap(o -> o, Function.identity()))

Any leads or better ways that doesn't require a manual map creation is appreciated.

My requirement:

In a webservice, return all the Enum values along with attributes to the client. The client has the logic to parse all the attributes coming. Like today there is a description attribute and tomorrow if new attribute like boolean manadatoryField, then it only needs to be handled by client. But from the server end, I am unable to return the Enum values with attributes without manually creating a map out of each enum and returning the map.

Upvotes: 0

Views: 1187

Answers (2)

Suman
Suman

Reputation: 868

Found a simple and another way of doing using Jackson:

Add annotations to the enum.

@Getter
@JsonFormat(shape = JsonFormat.Shape.OBJECT)

Add an explicit getter for name

public String getName() {
    return this.name();
}

new ObjectMapper().writeValueAsString(EnumExample.values()) returns a valid JSON which can be converted to Map. In my case I return, this to client!

Upvotes: 1

Suman
Suman

Reputation: 868

Answering my own question to help others. If this is the only way, then do upvote.

Arrays.stream(EnumExample.values())
      .map(enumExample -> 
              ImmutableMap.of("name", enumExample.name(),
                              "description", enumExample.description,
                              "value", enumExample.value))
      .collect(Collectors.toList())

Any best way to achieve the same without explicitly converting EnumExample to Map is greatly appreciated. For example, If any new attribute gets added then it should be coming in the resulting map as a new K, V pair.

Upvotes: 0

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