java.lang.ClassCastException: java.util.HashMap$EntrySet cannot be cast to java.util.HashSet

Question

I have following piece of code :

JsonObject json = (JsonObject) attVal;
HashSet<Map.Entry<String,JsonElement>> map = (HashSet<Map.Entry<String, JsonElement>>) json.entrySet();

I am getting below exception at line 2:

java.lang.ClassCastException: java.util.HashMap$EntrySet cannot be cast to java.util.HashSet

My json input is: {"key":"4e32cd954f31320078c5fd218110c7ca","number":"","unique_key":"001"}

What is the reason and how to solve this?

Do you specifically need a HashSet? What's wrong with the Set<Entry<String, JsonElement>> that's already returned? — Rogue
– Rogue, Commented Mar 28, 2017 at 8:18
Actually that was the Original code. The problem is Set is not Serialized which is the requirement. — code_fish
– code_fish, Commented Mar 28, 2017 at 8:29

m.antkowicz · Accepted Answer · 2017-03-28 08:03:10Z

1

HashMap$EntrySet has nothing common with HashSet and because of this casting fails

You should rather iterate over json's entry set and add following values to your HashSet

HashSet<Map.Entry<String,JsonElement>> map = new HashSet<>();

for(Map.Entry<String,JsonElement> entry : json.entrySet()){
    if(entry != null) {
        map.put(entry.getKey(), jsonObject.get(entry.getKey()));
    }
}

answered Mar 28, 2017 at 8:03

m.antkowicz

13.7k22 silver badges43 bronze badges

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

Collectives™ on Stack Overflow

java.lang.ClassCastException: java.util.HashMap$EntrySet cannot be cast to java.util.HashSet

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related