java change variable argument value

Question

I am not sure if I am doing some silly mistake, What I am trying to achieve is I have JSON list and I want to convert them into multiple objects depending on variable argument passed to function.

Unit u1= new Unit();
User us = new User();
//calling funtion
StaticUtil.MagicJsonMapper(list, u1,us);
System.out.println(u1.getUnitName()); //place -1 unitName is null after function call

Inside static class I have create a function

@SuppressWarnings("rawtypes")
public static void MagicJsonMapper(List list,Object... objects){
    if(list.size()!= objects.length){
        //TODO
        System.out.println("parame`ter mismatch");
        return;
    } 
    int i=0;
    ObjectMapper mapper = new ObjectMapper();
    for(Object object : objects){
        if(list.get(i) instanceof List){
            MagicJsonMapper((List)list.get(i),object);
        }
        else{
            objects[i] = mapper.convertValue(list.get(i), object.getClass());
        }
        i++;
    }
 //place -2 "objects" contains proper value of unitname 
}

The issue is I am still not getting proper value in parameter after finished running this method. It means argument values are not retained as in contrast of normal java behaviour, is it something to do with variable argument. Just for clarity I debugged the code and values are proper at the end of the function.

Not related, but you should respect Java convention and start your method name with a lowercase ;-) — Joffrey
– Joffrey, Commented Mar 22, 2015 at 10:28
"I am still not getting proper value in parameter after finished running this method" - can you show us how and where you try to access the value? — Joffrey
– Joffrey, Commented Mar 22, 2015 at 10:33

yole · Accepted Answer · 2015-03-22 10:21:55Z

3

The objects array is created during the function call and discarded afterwards. If you need to access the values from the array after the call, you need to create the array explicitly.

answered Mar 22, 2015 at 10:21

yole

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3 Comments

sanjay patel Over a year ago

The problem would be this code is to ease my efforts to unwrap each json and typecast. if I am creating array and passing it, then later I have to unwrap it and typcast which increase my job. Do you think there can be any other solution to this problem.

Joffrey Over a year ago

@sanjaypatel your JSON contains various types to read, and you seem to know them and their order (since you pass objects of each class to your method). I believe you should probably consider creating a class where all these objects are fields, instead of using a generic list or array.

sanjay patel Over a year ago

@Joffery: I creating a rest based application, my request to server can consist of n number of different probable combinations to different resource. I thought to make it more generic, with ur suggestion I will end creating many POJOs which I don't want as they might be used only once a while.

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