How to parse JSON to List with Maps in Gson? - json

Question

I have the following Java Classes:
public class ModuleParsed {
String id_component;
String id_instance;
Map<ModuleParam, ModuleParam> input;
Map<ModuleParam, List<ModuleParam>> output;
int id_paas;
}
and
public class ModuleParam {
String name;
Object type;
}
what should be the JSON expected to parse it as a List<ModuleParsed>?
listModules = gson.fromJson(br, new TypeToken<List<ModuleParsed>>() {}.getType());
Everything was ok until I introduced the input and output parameters.
EDIT
By doing the reverse process I have found the JSON should be something like
[
{
"id_component": "mod1",
"id_instance": "mod1_inst1",
"input": {
"moduleParam": {
"name": "param3",
"type": "obj3"
},
"moduleParam": {
"name": "param2",
"type": "obj2"
}
},
"id_paas": 1
},
{
"id_component": "mod2",
"id_instance": "mod2_inst1",
"input": {
"moduleParam": {
"name": "param3",
"type": "obj3"
},
"moduleParam": {
"name": "param2",
"type": "obj2"
}
},
"id_paas": 1
}
]
where the moduleParam elements were something like: parser.ModuleParam#36c51089
No matter how I name these elements I get the following error:
Exception in thread "main" com.google.gson.JsonParseException: Expecting object found: "moduleParam"
How can I obtain the class ModuleParsed with Gson?

Answer 1

Following #Brian's comment I realized I had no need to use complex objects as keys so this was my solution.
public class ModuleParsed {
String id_component;
String id_instance;
Map<String, ModuleParam> input;
Map<String, List<ModuleParam>> output;
int id_paas;
}
public class ModuleParam {
String name;
String id_module;
String id_instance;
}
for which I built the following JSON
[
{
"id_component": "mod1",
"id_instance": "mod1_inst1",
"input": {
"input1": {}
},
"output": {
"output1": [
{
"name": "input1",
"id_module": "mod2",
"id_instance": "mod2_inst1",
"type": "paramType"
},
{
"name": "input2",
"id_module": "mod2",
"id_instance": "mod2_inst1",
"type": "paramType"
}
],
"output2": []
},
"id_paas": 1
},
{
"id_component": "mod2",
"id_instance": "mod2_inst1",
"input": {
"input1": {
"name": "output1",
"id_module": "mod1",
"id_instance": "mod1_inst1",
"type": "paramType"
},
"input2": {
"name": "output1",
"id_module": "mod1",
"id_instance": "mod1_inst1",
"type": "paramType"
}
},
"output": {},
"id_paas": 1
}
]
The JSON was parsed correctly this time.