get object name

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finecur - 14 Jul 2007 18:15 GMT

Suppose I have:

List myList = new ArrayList();

What method of myList can I call to return the String "myList"?

Thanks,

ff

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Arne Vajhøj - 14 Jul 2007 18:32 GMT

> Suppose I have:
>
> List myList = new ArrayList();
>
> What method of myList can I call to return the String "myList"?

None.

The name of the reference is not part of the object.

And local variables loose the names already during
compilation.

Arne

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Lew - 14 Jul 2007 18:42 GMT

> Suppose I have:
>
> List myList = new ArrayList();
>
> What method of myList can I call to return the String "myList"?

None.

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Lew

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Patricia Shanahan - 14 Jul 2007 19:38 GMT

> Suppose I have:
>
[quoted text clipped - 5 lines]
>
> ff

"myList" is not a property of the ArrayList at all. A given object can
be referenced by several variables, with different identifiers.

There are several ways you could associate a String with an ArrayList. I
don't know which to recommend. Perhaps you could explain the higher
level problem you are trying to solve?

Patricia

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Roedy Green - 14 Jul 2007 23:35 GMT

>List myList = new ArrayList();
>
>What method of myList can I call to return the String "myList"?

the names of local variables don't exist in the class file, so this is
impossible without some preprocessing get it added. However the names
of instance and class methods and variables are in there.

See http://mindprod.com/jgloss/jpda.html
http://mindprod.com/jgloss/debugger.html

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Roedy Green Canadian Mind Products
The Java Glossary
http://mindprod.com

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Piotr Kobzda - 15 Jul 2007 08:53 GMT

>> List myList = new ArrayList();
>>
>> What method of myList can I call to return the String "myList"?
>
> the names of local variables don't exist in the class file,

Don't exist in all class files, because the LVT (LocalVariableTable) is
an optional part of a class file (assumed a part of a debugging info).

> so this is
> impossible without some preprocessing get it added.

Java compiler (javac) can do that with -g switch (-g:vars is enough).

> However the names
> of instance and class methods and variables are in there.

With local variable debugging information present, the names of local
variables (and method parameters) are also in there. It just requires a
bit more effort to retrieve them, an example is there:
http://tinyurl.com/yqgz3q

piotr

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Roedy Green - 15 Jul 2007 00:50 GMT

>List myList = new ArrayList();
>
>What method of myList can I call to return the String "myList"

As others have told you Objects don't have names, and since references
can point to different objects in their career, there is no simple
association between reference name in the source code and Objects.

However, there is a case where Objects can be assigned names. It is a
little used feature. Component.setName. I used it back in the days of
Java 1.0 to automatically attach labels to fields.

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Roedy Green Canadian Mind Products
The Java Glossary
http://mindprod.com

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get object name

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