Question

Does anyone know of a class in Java that has a list of elements, so that the elements are sortable by any of the elements members? The idea is basically to have some database table-like implementation, where you can just add fields to sort by. To illustrate:

SomeTable table = new SomeTable(); table.addField('name', String); table.addField('age', int); table.addField('hair color', String); table.add(new Object[]{'Thomas', 32, 'brown'}); table.add(new Object[]{'Jack', 34, 'black'}); 

table.sort('age') would sort the table so that Thomas is the first element, while table.sort('name') would sort the table so that Jack is the first element.

I can code something like this myself (actually I have done that once), but I’m just curious to see if there’s a ready library to do such things (without a database).

PS: I know that int is not a class, but that’s not the point here. This example code is just here to show the kind of functionality I expect.

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Answer 1

The closest thing I can think of myself is the Apache Commons BeanUtils API. For example for a ‘student’ table.

  DynaProperty[] props = new DynaProperty[]{         new DynaProperty('firstName', String.class),         new DynaProperty('lastName',  String.class),         new DynaProperty('address', java.util.Map.class)        };     BasicDynaClass dynaClass = new BasicDynaClass('student', null, props); 

Given a collection table of these student objects. We define a BeanComparator

 BeanComparator surnameComparator         = new BeanComparator('lastname'); Collections.sort(table, surnameComparator); 

Not sure if this is what you’re looking for, but it seems pretty close.