Passing list object through intent with gson.toJson and gson.fromJson

GsonDecodeListObject.java

// passing to intent:
     b.putSerializable(BUNDLE_PARAMS, new Gson().toJson(params));     

// retrieving data: 
     List<KeyValueStringPair> params = new Gson().fromJson(b.getString(BUNDLE_PARAMS), new TypeToken<List<KeyValueStringPair>>(){}.getType())
     
// model class   
     public static class KeyValueStringPair implements Serializable {

        @SerializedName("_key")
        public String key;

        @SerializedName("_value")
        public String value;

        public KeyValueStringPair() {
          // compulsory empty constructor
        }

        public KeyValueStringPair(String key, String value) {
            this.key = key;
            this.value = value;
        }
    }