Convert object from a type to another by casting using java Field getType() method

Question

I am using ksoap2, and when I get a soap object that looks like:

params=anyType
{
  defaultValueString=10; 
  label=Number of search results; 
  optional=true; 
  PRName=Yahoo PR; 
  paramName=limit; 
  pipelineName=Yahoo Search; 
  type=int; 
};

I try to change some fields in class using reflection, by using method setAttr:

The setAttr method is written:

public void setAttr(Object tag,Object value)
{
    Field dynamicSet = gateRuntimeParameter.class.getField((String)tag);

    dynamicSet.set(new gateRuntimeParameter(),  value);

}

The problem is tag would sometimes be lets say: boolean, but value is an soapprimitve object type...

How can I cast value using field getType, i.e. something like: (dynamicSet.getType())value?

AdamH · Accepted Answer · 2011-03-15 23:29:07Z

1

You'll have to write custom coercion code to do this. Trying to simply cast the value won't be possible, since it would require rules to handle cases like casting boolean to int. You'll need to write a method something like this:

public Object coerce(Object value, Class<?> coerceTo) {
    if (Boolean.class.equals(coerceTo)) {
        //coerce soap primitive to Boolean
    }
    else if (Integer.class.equals(coerceTo)) {
        //coerce soap primitive to Integer
    }
    else if (List.class.equals(coerceTo)) {
      return Collections.singletonList(coerce(value, coerceTo.getTypeParameters()[0]));
    }
}

Note that java's auto-boxing/unboxing will mean you don't need to worry about handling the int case separately to java.lang.Integer, just handle java.lang.Integer and java will auto-coerce to int if required.

edited Mar 15, 2011 at 23:29

answered Mar 15, 2011 at 23:07

AdamH

2,20116 silver badges14 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

ccot Over a year ago

thx for the help, but how do you coerce in a case where you have a type: List<Object> ??

AdamH Over a year ago

@Chadic Hm, I think something like this might work, but untested

if (List.class.equals(dynamicSet.getType())) { return Collections.singletonList(coerce(value, dynamicSet.getType().getTypeParameters()[0])); }

. You'll probably want to factor out your coerce method so it can take the Class type to coerce to as a parameter, then you can recurse onto it for Collection types. I think dynamicSet.getType().getTypeParameters()[0] should give the generic type declared on your method (if you've declared them).

AdamH Over a year ago

@Chadic I've updated the original answer to give you a clearer idea of how to handle collection types. It's untested, I'm not sure if type erasure will prevent this from working, but it's worth a try.

ccot Over a year ago

thx a lot man , it works ( i still didnt test the list part but i will soon) :)

Collectives™ on Stack Overflow

Convert object from a type to another by casting using java Field getType() method

1 Answer 1

4 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

4 Comments

Your Answer

Sign up or log in

Post as a guest

Related