GSON ClassCast Exception cannot cast from object to string

Question

        List<Object> l = new ArrayList<Object>();
        l.add("abc");
        String s = (String) l.get(0); /////// No Exception here
        System.out.println(l); 
        String json = gson.toJson(l);
        System.out.println(json);
        Type t = new TypeToken<List<Object>>() {
        }.getType();
        List<Object> dl = gson.fromJson(json, t);
        String ds = (String) dl.get(0); /////Class Cast Exception here

Doing something like the above one. I am trying to serialize a list of Objects. First element in that is a String, but when I deserialized the list and reading the first element to a string it's throwing a classcastexception. And there are no exceptions when reading the first element to a string before serializing.

What's the reason behind this?

Have you stepped through this code line-by-line to see what might be gling on? — Tim Biegeleisen
– Tim Biegeleisen, Commented Apr 19, 2015 at 14:01
Give the EXACT and COMPLETE error message. And show us the JSON. — Hot Licks
– Hot Licks, Commented Apr 19, 2015 at 14:41
This is the error message:Exception in thread "main" java.lang.ClassCastException: java.lang.Object cannot be cast to java.lang.String — vjk
– vjk, Commented Apr 19, 2015 at 17:01
If you have an Object, that did not come from JSON. (Unless GSON uses Object as a "null" value or some such -- I'm not up on all the various JSON kits and their quirks.) Again, where is the JSON? — Hot Licks
– Hot Licks, Commented Apr 20, 2015 at 19:08
I don't get any error when running this code. Which version of Gson are you using? — Alexis C.
– Alexis C., Commented Apr 21, 2015 at 10:19

vjk · Accepted Answer · 2015-04-24 19:56:37Z

1

I have an older version of GSON 1.4.

Updating it to 2.2.4 version worked.

answered Apr 24, 2015 at 19:56

vjk

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