Swing Hacks

Size Your Columns to Suit Your JTable’s Contents #21

Chapter 3, Tables and Trees

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HACK

If it does, then we have a usability problem to discuss. By default, the col-

umns of a

JTable are all the same size. For this data, that’s obviously a terri-

ble decision—there’s far too much space reserved for the numbers in the

count column, and not nearly enough in the URL column. So, how are you

going to fix this?

If you said “turn on the horizontal scrollbar,” please close this book, grasp it

with both hands, and firmly smack yourself in the head with it. No, you are

not turning on the horizontal scrollbar! Use the pixels available to you

before you resort to the user-annoying desperation of horizontal scrolling. In

this case, the count column has lots of pixels to spare; you just need to real-

locate this extra space to the URL column.

Resetting Column Widths

What makes programmatic column resizing difficult for many Swing pro-

grammers is that they can’t even find the right methods to use. If all you ever

work with is

JTable (and maybe a few custom cell renderers), you’ll notice

that the JavaDoc for those classes says nothing about column widths. The

problem may be that the

JTable is so generous with helpful methods that

you’d never even notice that it’s made up of

TableColumn objects. Take a

look at that

TableColumn’s JavaDoc, and you’ll find getters and setters for

minimum, maximum, and preferred widths for ...