Question

I have some collections that I would like to analyze in the Eclipse debugger. I am interested in a particular attribute of each element.

Let’s take an example with a list of Persons (each one with an address attribute which in turn has a city attribute). In the debugger I can either look at each element or look at list.get(i).address.city.

Doing this for large structures is not really helpful. Is there the possibility to apply a function to a data structure, something similar to the map function in Perl (in the debugger not in the code).

The input would be my list with the path I am interested in (Person.address.city), the output a list with just the selected elements (a list of cities with my example).

In Perl:

map { $_->{address}->{city} } @list

Edit

I am able to generate a String with a Detail Formatter:

StringBuilder sb = new StringBuilder();
for (Person p : this) {
    sb.append(p.address.city());
    sb.append(", ");
}
return sb.toString();

This will format my list with just the elements I am interested in (as a String).

Although it goes in the right direction it would be nice if I could return a new List that I can analyze with the debugger.

Answer 1

I think, the Eclipse Debugger feature you are interested is called logical structures. You could define a logical structure in Eclipse preferences (Java/Debug/Logical structures), where you could write such an expression (hopefully), and then on the variables view you could replace the display of the list in the pop-up menu.

See this blog post for basic ideas: http://www.javalobby.org/forums/thread.jspa?threadID=16736&messageID=91823528