将json对象转换为java对象

Question

class A{}

class B{}

class C{ 
       private Map<A,B> myMap;
   }

class Test{

public static void main(String [] args)
{ 
      Map classMap=new HashMap();
       classMap.put("myMap","?");
       C c = (C) JSONObject.toBean(jsonObject, C.class,classMap);
}

}

I am using "net.sf.json" library for converting json object into java object.Here in class C there is a map, so how to convert it into Java Object. Here jsonObject is a json representation of class C. My question is how to convert a json object into Java Object if java Object containing Map

I am a beginner, any help will be very thankful.

Answer 1

I have used jackson library and in that when a json is passed to the java code and if you want to parse that json into a java object you need to have a class which contains all the property which are present in the json string.

for example:

jsonString=
{
 'firstname':'json',
 'lastname':'jack'
}

will be equivalent to a java class which contains both the property as

class A {
 String firstname;
 String lastname;
}

so if you accept the string from frontend as the object of class A it works

like

public void (A objectofA){

}

and you call this method from front end and pass a json string using json library it will work and have faith in your work.

Answer 2

I don't know how to do it in "net.sf.json" Try to see how serialization works in "net.sf.json". Probably, you can go from there.

This is how it is done using jackson, (one of the commenters has tried to explain you an approach using this)

//you need to import:
//import org.codehaus.jackson.map.ObjectMapper;

ObjectMapper mapper = new ObjectMapper();
mapper.writeValueAsString(c) //--> This gives Json String

Answer 3

I don't think this can work, as JSON cannot represent arbitrary objects as keys in maps. In JSON keys have to be strings. So in your example Map would only work if A was String.

Then you could say:

classMap.put("myMap",B.class);