Simple class to handle Json
Here are some suggestions


be consistent: jsonStr vs. jsonString
be consistent: GetObjFromJson vs WriteObjAsJson (maybe Read &amp; Write instead)
use guard clauses instead of nesting
avoid temporary variables like successfulWrite and retObj


Based on the suggestions, here is one alternative:

static class JsonHandler // class could be static
{
    public static T GetObjFromJson&lt;T&gt;(string filePath)
    {
        // use a guard clause to reduce nesting
        if (File.Exists(filePath)) return default(T);

        try
        {
            var jsonStr = File.ReadAllText(filePath);

            // guard clause again
            if(string.IsNullOrWhiteSpace(jsonStr)) return default(T);

            // we could use null coalesing operator ?? here
            return JsonConvert.DeserializeObject&lt;T&gt;(jsonStr) ?? default(T);
        }
        catch (Exception ex)
        {
            // do proper exception handling
        }

        return default(T);
    }

    public static bool WriteObjAsJson(string filePath, object obj)
    {
        try
        {
            string jsonStr = JsonConvert.SerializeObject(obj);
            File.WriteAllText(filePath, jsonStr);
        }
        catch (Exception ex)
        {
            // do proper handling
            return false;
        }

        return true;
    }
}


Also you should think about exception handling.


if the method returns default(T), maybe reflect that in the method name
if the method throws on failure, maybe wrap the exception into a custom one
if the method fails, return null to signal that
use the Try* pattern, look at bool int.TryParse(string,out int)


Also, in the DummyClass you can use Auto-Implemented Properties public string Name { get; set; }