Swing Hacks

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Chapter 3, Tables and Trees

#23 Let Your JTables Do the Sorting

HACK

H A C K

#23

Let Your JTables Do the Sorting Hack #23

Why doesn’t Swing already offer this? Oh well, here’s how to do it yourself.

It’s hard to imagine you’ll do much serious work with JTables without need-

ing to sort the contents by one of the columns, or support changing between

columns to use as the sort criteria. In fact, given how generous the Swing

API usually is, it’s kind of surprising that it doesn’t already offer it. Oh well,

it’s not that hard to do for yourself.

There are a couple of approaches you could take to solve this problem. You

could create a subclass of

TableModel, one that keeps an internal Comparator

to do the sorting and resorts every time an add( ) or remove( ) type method is

called. The drawback to this approach is choosing which of the model

classes to subclass. If you go too high up the hierarchy by implementing

TableModel or subclassing DefaultTableModel, you would miss some typical

Swing functionality that developers expect, like the ability to add and

remove rows provided by

DefaultMutableTableModel. On the other hand, if

you subclass

DefaultMutableTableModel, other developers will be unhappy

because subclassing your class requires them to pick up public

add( ) and

delete( ) type methods that expose their data in ways they don’t want.

So, consider an alternative: two table models, one that the

JTable