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JsonArray.getvaluesAs does not take String.class parameter as parameter

I am using javax.Json.JsonArray

object.

method: javax.Json.JsonArray.getvaluesAs(Class<T>)

returns JsonArray

as List. So I want to do List

in Set

. this is what i am doing:

Set values= new HashSet(myjsonArray.getValuesAs(null));

This works great, but I know it myjsonArray

only contains String

. so I really want:

Set<String> values= new HashSet(myjsonArray.getValuesAs(String.class));

For some reason, for the above code, I am getting a compiler error:

The generic method getValuesAs(Class<T>) of type JsonArray is not applicable for the arguments (Class<String>). The inferred type String is not a valid substitute for the bounded parameter <T extends JsonValue>

I can create mine Set<String>

built using loops, but I try to avoid it, so is there an easy fix for the error above?

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3 answers


The getValuesAs () method only supports classes that extend JsonValue. In this case, you can use JsonString.class, which then just passes the string.



Check this out ( http://docs.oracle.com/javaee/7/api/javax/json/JsonArray.html#getValuesAs-java.lang.Class- ) and you could see T extends JsonValue

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I have used this library a long time ago. From what I remember, you can only pass the class to the getValuesAs () method, which extends from JsonValue. This is why the line doesn't work. You will have to try another method. Sorry, I don't remember which method exactly.



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As Nine said the getValuesAs () method only supports classes that extend JsonValue "

Here's my work (and the only one possible) for this problem:

private static List<String> toList(JsonArray json){
    List<String> list = new ArrayList<String>();
    if (json != null){
        for (JsonString elm: json.getValuesAs(JsonString.class)){
            list.add(elm.getString());
        }
    }
    return list;
}
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