deserialize a generics hashmap when key is not primitive

[yuval]

Hi

I want to gson and de-gson a hashmap with generics.
I can do it successfully when my key is a string but not if it is an
object.
I have the two code part here . the first doesnt work and the second
does.
First throws an
I implemented the
// doesnt work works - with string
try {
TradableBean tradable = new TradableBean("Tradable");
PositionBean position = new PositionBean(tradable);
Map<TradableBean, PositionBean> map1 = new
HashMap<TradableBean, PositionBean>();
map1.put(tradable, position);
String json1 = gson.toJson(map1);
Map<TradableBean, PositionBean> map2 =
gson.fromJson(json1, new TypeToken<Map<TradableBean, PositionBean>>()
{}.getType());
System.out.println(map2);
} catch (Exception e) {
System.out.println("failed");
}
// works - with string
try {
String tradable = new String("Tradable");
PositionBean position = new PositionBean(new
TradableBean("Tradable"));
Map<String, PositionBean> map1 = new HashMap<String,
PositionBean>();
map1.put(tradable, position);
String json1 = gson.toJson(map1);
Map<String, PositionBean> map2 = gson.fromJson(json1, new
TypeToken<Map<String, PositionBean>>() {}.getType());
System.out.println(map2);
} catch (Exception e) {
System.out.println("failed");
}

and in the TradableBean I have :

@Override public int hashCode() {
return getId();
}
@Override public boolean equals(Object obj) {
boolean equals = false;
if (obj instanceof AccountBean){
TradableBean tradable_p = (TradableBean)obj;
if (getId()==tradable_p.getId()){
equals = true;
}
}
return equals;
}

the exception

com.google.gson.JsonParseException: Expecting object found:
"TradableBean{id=0, tradableName='Tradable', moneyMultiplier=1,
expirationDate=null}"
at
com.google.gson.JsonObjectDeserializationVisitor.visitFieldUsingCustomHandler(JsonObjectDeserializationVisitor.java:
100)
at
com.google.gson.ObjectNavigator.navigateClassFields(ObjectNavigator.java:
150)
at com.google.gson.ObjectNavigator.accept(ObjectNavigator.java:123)
at
com.google.gson.JsonDeserializationContextDefault.fromJsonPrimitive(JsonDeserializationContextDefault.java:
84)
at
com.google.gson.JsonDeserializationContextDefault.deserialize(JsonDeserializationContextDefault.java:
53)
at com.google.gson.DefaultTypeAdapters
$MapTypeAdapter.deserialize(DefaultTypeAdapters.java:531)
at com.google.gson.DefaultTypeAdapters
$MapTypeAdapter.deserialize(DefaultTypeAdapters.java:498)
at
com.google.gson.JsonDeserializerExceptionWrapper.deserialize(JsonDeserializerExceptionWrapper.java:
50)
thank you.

[nischalshetty]

Does this help?

http://goo.gl/Ai0RB

-N

[Joel]

Gson 1.7 has a new feature that better supports complex map keys. See
http://groups.google.com/group/google-gson/browse_thread/thread/6272c9be58676e47
for the announcement that contains an example of how this feature
works.