Re: How do I determine the owner of an object?

Mark Space <>
Wed, 10 Oct 2007 21:14:11 GMT
Todd wrote:

If it can be done, how do I determine the class within which an object
was instantiated?

The desired output would be:

None such, as others have said. Don't forget though that there's no
difference between using a reference of type Double and using a
reference of type Example1. (I think Array references typically do use
up a bit more memory though.) So if you have the parent reference
anyway, you might as well pass that.

For example:

     Example1 ex1 = new Example1();
     Example2 ex2 = new Example2();

     Vector<Double> values = new Vector<Double>();
     values.add( ex1.getValue() );
     values.add( ex2.getValue() );

Try this:

interface Example {
    public Example getParent() {};

class Example1 extends Double implements Example
    Double value = new Double( 12.34 );
    public String toString() {
        return value.toString();
    Example1 getParent() {
        return this;

And similar for Example2. Then you can:

     Iterator<Double> valueIter = values.iterator();
     while( valueIter.hasNext() )
         Double value =;

         System.out.println( "value's owner class is: "
        + ((Example)value).getParent()
        .getClass().simpleClassName() );

I think this technique might work. Haven't tested it out in detail.

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