java.lang.NoClassDefFoundError: com/fasterxml/jackson/dataformat/yaml/YAMLFactory | Together Java | Page 1

halcyon scaffoldBOT Jul 16, 2023, 9:42 AM

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<@&987246399047479336> please have a look, thanks.

halcyon scaffoldBOT Jul 16, 2023, 9:42 AM

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halcyon scaffold <@&987246399047479336> please have a look, thanks.

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wary jackal Jul 16, 2023, 10:05 AM

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yes. and the full exception

wary jackal Jul 16, 2023, 10:31 AM

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why is the maven dependency yellow?

timber crescent Jul 16, 2023, 10:34 AM

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where is maven?

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sorry, misunderstanding

manic verge Jul 16, 2023, 11:53 AM

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small sidequestion, are u using VC code ?

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and line 45 of discordveri... is what ? ( no line numbers on any screenshot )

manic verge Jul 16, 2023, 1:32 PM

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with the small section u posted its quite hard to help. But since your using a file, i'd start looking there with debug mode

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<dependency>
<groupId>com.fasterxml.jackson.dataformat</groupId>
<artifactId>jackson-dataformat-yaml</artifactId>
<version>2.13.0</version>
</dependency>

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version might be wrong, but do u have it ?

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2.15.2 is latest, did u update your maven after adding that section ?

manic verge Jul 16, 2023, 2:17 PM

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what is this ?

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https://i.imgur.com/7q5cHKT.png

Imgur

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so 4 strings from another source ?

ivory hill Jul 16, 2023, 4:00 PM

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make sure you right clicked + refreshed deps?

ivory hill Jul 16, 2023, 4:43 PM

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I mean, it seems like somehow the dependency just isn't there?

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What are you using the yaml for?

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Maybe we can take a stop and make Json work

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Then get back to the yaml

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well tbh this should work as is

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hence why i want you to switch back to json for a moment, since it will rule out any issues with the yaml integration

wary jackal Jul 16, 2023, 7:38 PM

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it has a lot of odd choices in it, that's for sure

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and some legacy things

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File class, casts, using nodes instead of letting it deserialize to a pojo automatically,...

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also catching exception

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all of what i just said should be redone properly

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not just that aspect

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anyways. to fix ur problem at hand, it would be helpful to understand what the problem actually is

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so please describe it in more detail

ivory hill Jul 16, 2023, 7:50 PM

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oh i see whats happening

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hashmap.put returns a value

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and thats what is being written

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ObjectMapper objectMapper = new ObjectMapper();
HashMap<String, String[]> m = new HashMap<>();
m.put(k, v);
objectMapper.writeValue(new File(CLIENTS_YML_PATH), m);

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try this

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inside the try

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.put returns the previous value associated with the key or null if there is no previous value

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so when you do new HashMap<>().put(...) you get null

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which is all the hint i need to say this

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STOP FUCKING USING CHAT GPT TO WRITE CODE FUCK

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AAAGHGHGH

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objectMapper.writeValue(new File(CLIENTS_YML_PATH), Map.of(k, v));

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this will work too

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yeah and chat gpt doesn't know about it

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since it learned java from all the shitty articles ever written and the horrible 90s codebases

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also - if you don't need yaml consider using my json library

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nah its good

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i just made a library specifically tailored for beginners

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try (var writer = Files.newBufferedWriter(Path.of(CLIENTS_YML_PATH))) {
   Json.write(
       writer, 
       Json.objectBuilder()
         .put(k, Arrays.stream(v).map(Json::of).toList())
         .build()
   )
}

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i think objectMapper.readValue(???, String[].class)

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or just

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actually

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objectMapper.readValue(file, new TypeToken<HashMap<String, String[]>>() {})

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for jackson

wary jackal Jul 16, 2023, 8:00 PM

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or just create a pojo like any sane person would do

ivory hill Jul 16, 2023, 8:00 PM

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well in this case isn't the set of keys open?

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im not sure the annotation that "flattens" things

wary jackal Jul 16, 2023, 8:00 PM

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in which case u should alter the json. cause json with undefined keys is horrible bullshit

ivory hill Jul 16, 2023, 8:01 PM

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@JsonCreator
record Stuff(HashMap<String, String[]> value) {}

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i think

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and then read in Stuff.class

wary jackal Jul 16, 2023, 8:01 PM

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its just a shitty data model

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do proper json

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with well defined keys and then working with it is simple

ivory hill Jul 16, 2023, 8:01 PM

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key value pairs are fine - idk what they are using them for tho

wary jackal Jul 16, 2023, 8:02 PM

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keys are not values

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bad:
{
day0: 30,
day1: 27,
day2: 35
day3: 21
}

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better:
{
measurements: [
{ day: 1, temp: 30},
{ day: 2, temp: 27} ,
...
]
}

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and suddenly its super easy to work with

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and u can serialize in a single simple line of code with a pojo

ivory hill Jul 16, 2023, 8:05 PM

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yeah - jackson really guides you to certain json structures

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since some are easy to work with, some suck

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public class Main {
    static String CLIENTS_YML_PATH = "test.json";

    public static void main(String[] args) throws IOException {
        Map<String, String[]> stuff;
        try (var reader = Files.newBufferedReader(Path.of(CLIENTS_YML_PATH))) {
            Json json = Json.read(reader);
            stuff = JsonDecoder.object(
                    json,
                    JsonDecoder.array(JsonDecoder::string)
                            .map(list -> list.toArray(String[]::new))
            );
        }

        System.out.println(stuff);
    }
}

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anyways

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this is how you would do that with my library

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where everything is uniformly painful

pure surge Jul 16, 2023, 8:40 PM

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ivory hill ```java @JsonCreator record Stuff(HashMap<String, String[]> value) {} ```

no, each time you try to use jackson, you mess up 🙂

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you shouldn't need any annotation

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depending of what you want

marsh sun Jul 16, 2023, 8:48 PM

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the only annotation you really need is JsonProperty on some fields for mapping json name with variable

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right?

ivory hill Jul 16, 2023, 8:48 PM

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pure surge no, each time you try to use jackson, you mess up 🙂

For this case they want a top level Map<String, String[]>

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Afaik the ways to get that are

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Hash map subclass
Type token
Some annotation (which I think is Json creator)

pure surge Jul 16, 2023, 8:50 PM

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ivory hill 1. Hash map subclass 2. Type token 3. Some annotation (which I think is Json cre...

no, you don't need any annotation

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i think

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try and see i guess

ivory hill Jul 16, 2023, 8:55 PM

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im pretty sure without the annotation it will look for

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{
  "value": {
    "a": [ "b", "c" ],
    "d": [ "e" ]
  }
}

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when what you want is for it to read

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{
    "a": [ "b", "c" ],
    "d": [ "e" ]
}

pure surge Jul 16, 2023, 9:16 PM

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ivory hill ```java { "value": { "a": [ "b", "c" ], "d": [ "e" ] } } ```

it will infer it

ivory hill Jul 16, 2023, 9:20 PM

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it will not

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just tested it

pure surge Jul 16, 2023, 9:24 PM

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ah I see

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there is a weird behavior happening here

ivory hill Jul 16, 2023, 9:25 PM

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json creator wont work either for some reason

pure surge Jul 16, 2023, 9:25 PM

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yes that's normal

ivory hill Jul 16, 2023, 9:25 PM

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jackson really guides you to certain json structures
since some are easy to work with, some suck

but i don't think this claim is just me being bad at jackson

pure surge Jul 16, 2023, 9:26 PM

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it's because it's a record

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when you have a record, jackson except that it basically match the json, because a record represents data

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there are three things you can do here :

ivory hill Jul 16, 2023, 9:27 PM

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public record StuffFlat(Map<String, String[]> value) {
    @JsonCreator
    public static StuffFlat from(Map<String, String[]> value) {
        return new StuffFlat(value);
    }
}

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that works, but this doesn't

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public record StuffFlat(Map<String, String[]> value) {
    @JsonCreator
    public StuffFlat {
        
    }
}

(+ still doesn't with the args written/overrode)

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so thats interesting and fun

pure surge Jul 16, 2023, 9:29 PM

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it's because it's a record
when you have a record, jackson except that it basically match the json, because a record represents data
there are three things you can do here :

Use a factory :

record Container(Map<String, String[]> values) {
    @JsonCreator
    public static Container foo(Map<String, String[]> values) {
        return new Container(values);
    }
}

Use a class

class Container {
    Map<String, String[]> values;
    @JsonCreator
    public Container(Map<String, String[]> values) {
        this.values = values;
    }
}

Don't use a container :

Map<String, String[]> values = objectMapper.readValue(json, new TypeReference<>(){});

ivory hill Jul 16, 2023, 9:30 PM

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Make a container

class Container extends HashMap<String, String[]> {}

pure surge Jul 16, 2023, 9:31 PM

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ivory hill * Make a container ```java class Container extends HashMap<String, String[]> {}...

More like use inheritance 🤔

#java.lang.NoClassDefFoundError: com/fasterxml/jackson/dataformat/yaml/YAMLFactory